R12 to R134a conversion

[sdg3205]

What is needed to change the system over to R134a?

I checked out John's website and it would seem to suggest about $250 will get you everything you need minus refrigerant.

Any tips or tricks would be great. We don't have a A/C conversion thread on the .org site yet.

Cheers

[WelmoedJ]

R-12 molecules a a bit bigger than R-134A molecules.
The A/C hoses in our cars are for R-12.
Using R-134A in those hoses will slowly loose refrigerant due to those molecules escaping from the system through the hose wall.

It's not something you have to worry about.
Have the system checked each year for sufficient refrigerant and you will be fine.

What you need to do:
- Replace all O-rings in the system
- Replace the orifice (in the pipe to the A/C evaporator)
- Replace the accumulator (dryer)
- If in doubt: replace low and high pressure switch (so you don't have to go in there again)
- drain the compressor oil
And after re-assembling of the system:
- refill compressor with ester oil (150 grams)
- have the system pressurized with nitrogen (for about 2-24 hours)
- no leaks? then vacuumize the system
- fill the system with R-134A (approx. 850 grams) and have fluor added too (allows easy checking for leaks using special lamps and glasses).
- have the A/C temp checked and if not right, adjust the low pressure switch half a turn depending on the outcome

Have a cool system :)

[David T]

If the hoses weren't 30 years old they *might* be OK but they are too old and leaky and with the higher pressures and hotter temperatures you have to run -134 at they will leak too much. Replace with newer "barrier" type hoses. The conversion is doable but just be aware you will lose about 10% cooling capacity. A better choice would be to stick with -12 or a drop-in replacement like R-414b. The hoses should be replaced in all cases along with the accumulator/dryer. If the inside of the system is nice and clean you probably should not try to replace the orifice tube. VERY high risk of damaging the pipe and then having to replace the evap core. Not a fun job. Make sure both coils are clean. Make sure the cooling system for the motor is working well too.
David Teitelbaum

[DMCVegas]

Everything WelmoedJ said, but to add a couple of things:

*You need to FLUSH the system out, not just drain it. Mineral and Polyester oils don't mix.
*Skip the Orifice Tube and go with a Variable Orifice Valve type tube.
*You can Nitrogen Charge the system, but if you're in that much doubt about the system's ability to handle those pressures, replace all of the hoses.

Lots of people will swear up and down the R-134a doesn't keep a car as cool as R-12. But this is not true. Certainly there are a couple of things to know about the physical properties of this gas. The same volume of gas doesn't always absorb the same about of BTUs as R-12, and the gas is of a different viscosity. However that is why you have to adjust the system to accept this new gas. WelmoedJ hinted at this with the adjustment of the Low Pressure Switch. For full details, read the EPA Tips for R-134a Conversions. (http://www.epa.gov/ozone/title6/609/oneshop.html)

As you'll see R-134a cools just as well as R12 if not better in some instances. On certain RWD cars the High Pressures were 10-15% higher, as well as the Duct Temps @ Idle were 2-4 degrees warmer. That's because RWD vehicles back then ALWAYS used belt-driven fans, and if their clutches didn't get engaged by the engine temperatures, they wouldn't allow the A/C to run optimally by removing all of the heat from the gasses. None of this will be a Problem with the DeLorean since it uses electric fans like a FWD car that kick on whenever the A/C is activated.

[DniveK]

I used John's kit to convert my car last year. Get the spliced lines for easiest install. My car blows cooler now than it ever did with R12. I pulled a vacuum on the system for an hour or so while I ate lunch then checked for leaks by monitoring vacuumm gauge. Filled the system...done. The whole process took me about half a day to install, the lines to the front being the biggest pain. Good time to reseal your airbox with new foam. I popped out the passenger seat when doing the interior airbox work so its a bit more comfortable to work on.

[Exolis]

Do you also need to (or recommended to) flush the lines, just to make sure everything is cleaned out? DMCVegas mentioned the system, but not sure if implied to just Compressor or everything. If everything, I assume Ester Oil and some kinda pump?

And how do you pressurize with Nitrogen? (i.e. Pepboys, R-134a Refil Can like method, etc)

Sorry for all the specific questions, just want to make sure everything works perfectly and I know more about electrical stuff then Thermo/Fluidynamics. lol

[jawn101]

I also got John's kit with the split hoses. Replaced everything but the evaporator and condenser. Vacuumed it all out, cut the old lines with a razor. New lines laid in pretty easily. New o-rings, dryer, oriface tube and compressor. Pulled a vacuum and filled with refrigerant As you said, the only thing not included is the refrigerant and a vacuum pump/manifold gauges. You will probably also need a can adaptor to fit whatever kind of refrigerant you buy to your manifold gauge set. Harbor Freight has the pumps and gauges, but up in BC you may check Canadian Tire. I got mine off Amazon.

Aside from accidentally kicking over the container of PAG oil he included and having to run out for more it went smoothly. Ran very well for a few weeks and then lost its charge - turned out to be a not quite tight enough connection at the accumulator. It's quite hard to get in there but stick with it. Once I got that extra 1/4 turn on the hose the system is tight and ice cold. Hervey includes it all. Walmart is currently selling R134a for quite a savings over the other auto parts stores, at least here in CA. Again, in BC YMMV.

[outatym2001]

what is needed to change the system over to r134a?

Everything!

I’ve owned my D for eleven years and I eventually replaced everything but the Evaporator (kitchen sink) which is buried inside the black plastic casing with the Heater Core in the dash.
I tried it piece meal at first and had the Compressor changed, the Accumulator changed and everything cleaned out. It held the R134a gas for a while but it eventually leaked out.
So then I personally changed all the O-rings at all of the connections with the O-rings that are recommended for R134a. A long while later it all leaked out.
Bought more R134a and some time later the longest A/C rubber hose in the system from the Compressor to the Condenser sprung a leak and all the gas was gone. AAAaaaaarrrrrgh!
At this time I bought all three New Barrier Hoses and the Condenser designed for R134a from John Hervey.
From DMC Northwest I bought the Orifice Tube, a new Low Pressure Switch and another Accumulator.
Every time your A/C system is open to the outside air (atmosphere) you have to change the Accumulator.

Bought Interdynamics Arctic Freeze Ultra Synthetic R134a in 12oz cans at the local auto parts store. Believe I bought three cans. Then had a friend of mine who is an auto mechanic evacuate my A/C system with his evacuator that plugs into his air compressor. Then he used his A/C High/Low analog dial indicators to charge the system with R134a while the engine is running and A/C is set to max and fan speed is set to 4.

[stevedmc]

I guess the first question should be, what are your reasons for converting to r134a? Once we have an answer to that then we can properly answer what you will need to do the conversion.

If your r12 system is working perfectly fine then you will need less stuff to do the job.

If your r12 system is having problems, then you will need more stuff to do the job.

[Cory W]

The thing that people need to be aware of is that you probably would be in less trouble caught with 100 kilos of cocaine than one bottle of R12 in Canada. R134A is getting to be the same. They aren't in the public domain, and are heavily regulated. (Ironically enough, it's perfectly acceptable to purchase the propane based stuff off the shelf with no trouble at all) The invisible line makes all the difference (maybe it's worth a cross border refill?)

FWIW, I replaced my entire system two years ago, and it blows cold, even on those 35C+ degree days.

I got all three hoses, accumulator, and evaporator from Hervey, the rest through DMC Midwest, and have never looked back.

If you're going to do it, go all out and remove all doubt. The time you spend is well worth it.

[dmc6960]

$1000 doing every single component except evaporator, of which I still went through the trouble to remove and clean. Combined with new radiator and cooling fans and a VOV, excellently cold r134a system going on 6 years now. Completely untouched since the conversion.

[stevedmc]

All of this change out everything is a load of bull.

I'm still rocking with my original compressor, hoses, and evaporator. The only things new in my system are the condensor (due to me running over bambi), accumulator and orrifice tube.

I do have a minor leak that requires one or two cans of r134a a year ($8 per can), but that is a whole lot cheaper than spending $200-$300 for hoses and whatever other stuff you guys are replacing.

About the only thing I would recommend is replacing the condenser with a larger one if you do a lot of city driving. The purpose of the condensor is to cool down the refriderant. My condensor is stock (designed for r12) and it works fine because 90% of my driving is at highway speeds. Highway speeds push loads of air at my condensor and keep it cool. If you don't drive on the highway much, then you have to rely on your cooling fans to cool down the condensor. A bigger condensor would be good in this case.

But like I said, my stock AC system works fine. Ultimately all you need is a $5 adapter available at Walmart if your system is already working fine.

The reason I converted to r134a was convenience. My AC was working fine until I hit that stupid dear that put a dent in my condensor. I brought it to a shop that wouldn't touch the AC system because I had r12 in it. I decided to convert to r134a mainly for convenience, but of couse $8 a can is also much more affordable than $35 a can (I am a licensed AC guy btw, and I can buy all the r12 in the world if I want to and have the money).

End of rant. Sorry.

[sean]

I'm still rocking with my original compressor, hoses, and evaporator. The only things new in my system are the condensor (due to me running over bambi), accumulator and orrifice tube.

Did you omit the orifice tube or install a new one?

[dmc6960]

It is up to the individual to decide what they want to install. But with a 31 year old AC system, usually it needs a lot...

Compressor, single biggest "wear" item for an AC system. Fast moving parts, many different seals. I had over 90k miles on my car when I did my AC. My compressor clutch was failing, and the compressor itself was leaking. No brainer.

Condenser, second biggest "wear" item, though most people dont realize it. This part, being in the very front of the car, takes the brunt of road debris and insects, etc. Good airflow is ESSENTIAL here. Replacing it naturally freshens up its available airflow increasing its capacity, weather being replaced with a NOS or generic replacement. For the best performance you want the largest one which will fit and a "Parallel Flow" design for ultimate r134a performance. I dont believe anybody currently sells a compatible parallel flow condenser perfectly sized up. I will be helping someone else this year do a complete AC conversion and we'll be ordering a properly sized unit from a non-DeLorean vendor and adapting it to fit perfectly. I may also go back and replace my new (2006) condenser with one of these once we know the exact one to get.

Accumulator - A MUST replace during a conversion, no matter what. And a part that should usually be replaced when opening up any system for extended service.

Hoses - The original hoses just do not hold back the r134a. If you choose not to replace the hoses with new barrier hoses, you choose to refill with refrigerant every year. The person I'm assisting this year has previously converted to 134a replacing as little as possible at the time. Has had to add refrigerant every year. No other leaks in the system. He is completely unsatisfied which is why we are replacing everything now.

Cooling fans/radiator - While not directly part of the AC system, they play an extremely important role. You need good fans which can pull a lot of air. Dont fall for fans which are just advertised as "low current". They wont pull as much air, and that is the most important thing the fans do. Get the ones Toby at DMCNW has. Also consider your radiator, which if plugged with debris will not allow optimal airflow through the condenser. Also if original with plastic endcaps now is the best time to switch it out.

Evaporator - You gotta be careful here. These can easily spring a leak if the lines get twisted while trying to remove the hoses/accumulator. This could be justification to not replace much, but since the accumulator is the single most important thing to replace anyways, and you need to remove the high pressure line to get to the orifice tube, well justification lost then. Even if you do not replace the evaporator, it still should be cleaned out. A surprisingly high amount of debris gets in there. Your hands and a creative vacuum extension can work really good through the blow motor opening. However for the ultimate clean you need to remove it, which is of course a LOT of work, and at that point many people justify getting a new one anyways.

That was all my justification. Your mileage may vary.

[Henrik]

During my years as Application Engineer and Lab Manager for Sanden International (japanese owned company located in Wylie, TX and of course the manufacturer of the ancient SD-510 compressor) I headed up an EXTENSIVE R-12 to R134a test program from 1990 - 1993 that involved the full range of conversions, all the way from ""dirty conversion" (where we basically did nothing to the R-12 system, just charged it with R134a) up to a full system replacement with brand new parts designed/intended for R134a. We had cars running in Australia, Malaysia, Europe and in the US. All sorts of vehicles were used and regularly checked. The most significant contributor were probably the 18 wheelers that we had contracted through a trucking company that ran all across the US and were brought back and checked regularly. At the same time, we tested all sorts of conversions on our durability test benches, obviously under very tightly controlled conditions using a experimental modeling procedure that helped us discern what factors are significant and which ones were not. We also did a lot of performance comparisons in our climatic wind tunnel.

This program resulted in two Society of Automotive Engineers (SAE) Papers (#932906 "The Development of a Retrofitting Procedure for CFC-12 Automotive A/C Systems to HFC-134a and PAG lubricant" and #930230 "Vehicle testing: Retrofitting Mobile Air Conditioning Systems with HFC-134a" ) that were presented at the SAE convention in Detroit in late 1993. I am not saying this to relive old memories but for those of you who are wanting to do the conversion - here is the end result:

http://www.sanden.com/originals/images/retro.pdf

This retrofit procedure was the result of careful balance between cost, durability and performance.

[Chris4099]

I do have a minor leak that requires one or two cans of r134a a year ($8 per can), but that is a whole lot cheaper than spending $200-$300 for hoses and whatever other stuff you guys are replacing.

1-2 cans per year is a MAJOR LEAK, not minor. R-134a while not as bad as R-12 is still nasty stuff you don't want to release into the atmosphere at that rate. You are doing the environmental equivalent of driving several thousands of miles each year without actually going anywhere.

You must have forgotten your own thread when asking about environmental impact of refrigerants:
http://dmctalk.org/showthread.php?436-Are-refridgerants-such-as-r134a-and-r12-more-harmful-than-emissions-from-exhaust

[stevedmc]

Did you omit the orifice tube or install a new one?

Forgot to mention that. It came with the accumulator I think.


1-2 cans per year is a MAJOR LEAK, not minor. R-134a while not as bad as R-12 is still nasty stuff you don't want to release into the atmosphere at that rate. You are doing the environmental equivalent of driving several thousands of miles each year without actually going anywhere.

You must have forgotten your own thread when asking about environmental impact of refrigerants:
http://dmctalk.org/showthread.php?436-Are-refridgerants-such-as-r134a-and-r12-more-harmful-than-emissions-from-exhaust

One or two cans of 134 costs $8 to $16 a year and I have COLD ac. This is a small price to pay for staying cool.

Replacing everything costs about a thousand dollars. This is a high price to pay to stay cool in a car that many people barely drive at all.

The mileage between my two cars is at least 20k per year. I'm sure my driving is causing much more harm to the environment than a can or two of refrigerant.

[Chris4099]

The mileage between my two cars is at least 20k per year. I'm sure my driving is causing much more harm to the environment than a can or two of refrigerant.

Mileage driven has nothing to do with this. The point is you are causing damage that can be completely avoided. You can keep justifying that anyway you want, I can't stop you. Just know that 1-2 cans per year is not a minor leak and is causing a very specific amount of avoidable damage.

Personally, I rather enjoy not having to top off my AC system all the time. Knowing I did something right that doesn't require ongoing maintenance is also a good feeling too. It will be many more years before I have to touch the system again.

[jawn101]

..The point is you are causing damage that can be completely avoided. You can keep justifying that anyway you want, I can't stop you. Just know that 1-2 cans per year is not a minor leak and is causing a very specific amount of avoidable damage.

I think any licenced A/C guy should know better than to let this keep going on, for sure. Even the EPA 609 automotive refrigerant handling cert you get online is awarded based mainly on your agreement not to let the refrigerant escape.

[stevedmc]

Personally, I rather enjoy not having to top off my AC system all the time. Knowing I did something right that doesn't require ongoing maintenance is also a good feeling too. It will be many more years before I have to touch the system again.

Anyone who goes years without looking into their engine compartment is crazy. I usually glance in there every week or two just to check things like coolant and oil. It only takes 30 additional seconds to check refridgerant and is done maybe once a month during the summer months which doesn't really doesn't qualify as going in there "all the time".

Personally, I'd rather have the money to buy gas so I can afford driving the car. It amuses me hearing people cry about gas being $4 a gallon, yet they are willing to spend thousands of dollars on all sorts of other things.

[stevedmc]

And for the record, I never said he could get away with just converting without replacing any major parts.

He asked a question about converting and most everyone on here said "REPLACE EVERYTHING".

I simply asked if there is a problem with his existing system. If there is a problem then it needs to be corrected and that will cost more money.

If there isn't a problem, he may be able to doing it a lot cheaper which involves just a few things including:
1. "Properly" evacuate the refridgerant
2. He can flush the system out with mineral spirits and an air compressor if he chooses. I haven't done this.
3. Install adapter on low pressure side
4. Install adapter on high pressure side (optional)
5. Put a vacuum on the thing and let it sit overnight (or a few days/weeks) to see if it holds vacuum
6. Refill it

Those simple steps are a best case senario. Obviosly if the clutch on his compressor isn't working he will either need to replace the clutch or entire compressor.

If the system won't hold a vacuum overnight then he will obviously need to figure out where that major leak is. That could result in needing to change all sorts of stuff.

A more detailed process of what I wrote can be found here:

http://www.dmcnews.com/Techsection/r134_v2.html

[John U]

Since you are here in Canada, you can use RedTek (sold at Canadian Tire) which is essentially a Propane/Butane mix...it cools amazingly...I'm getting near freezing temps out of the vents. It is illegal in the US, but not Canada. Works well if your R12 system is still intact and not leaking terribly. I used it as a temporary measure as I was planning on switching to R134....that was over two years ago.

John

[Henrik]

Be careful, John:


which is essentially a Propane/Butane mix...

During the early 90s (here I go again) when a lot of companies were putting out retrofit blends on the market and before R134a became the de facto industry standard, I remember watching a video where they had a leaky A/C system charged up with a propane blend... someone threw in a lit cigarette and BOOM. The thing went up in flames. Not sure if this was actually outlawed in the US, but it was commercially dead at that point.

[QuadcityDMC]

It is outlawed.

I just had mine converted to r134. Big can of worms, new everything but condenser.

Save your money and go new everything.

[sdg3205]

Well it's probably about time I chime in on a thread I started. If I can the system will remain r12. If its going to cost as much to bring back the r12 system from the dead as it would be to convert to 134a I'll probably convert. I'm hoping I can get my r12 up and running without too much expense.

I was merely curious as to what other do-it-yourselfers had done and what people may have encountered elsewhere.

Thanks everyone for their input.

[David T]

If you go over the #'s it probably will cost more to convert to -134 and the worst part is you lose about 10% of your cooling capacity. The coils were not sized to use -134. As long as it is practical to continue to use -12 or a drop-in substitute it does not make sense to convert to -134. Maybe someday, but not now. Even with a conversion, I rarely see it done properly. You do not have to replace everything. You DO have to replace every "O" ring, flush out ALL of the oil and replace the hoses. You must change the service valves and attach a sticker indicating the conversion and the amount of -134 for a complete fill. Butane and Propane make a good refrigerant till you comprehend the dangers of even a minor leak. You will not need a leak detector to find the flame!!!!! Ammonia is also a great, cheap refrigerant. Too bad it's toxic! As it starts getting warmer we will see a lot more about this thread, we always do in the Spring.
David Teitelbaum

[stevedmc]

If you go over the #'s it probably will cost more to convert to -134 and the worst part is you lose about 10% of your cooling capacity.

It will cost less. r134a is $8 a can at Big Lots. r12 is about $35 a can if you can find it. The only additional expense to the silly "change everything" crap that everyone is spewing is the $5 adapter you need for the low side but keep in mind, it still ends up being cheaper overall because r134a is cheaper. I'm not super good at math but 3 x $8+$5=29 and 3 x $35= a lot more money.

My AC blows at 43 degrees while I am driving at highway speeds. This is with a new stock condensor. I wish I had gotten Hervey's larger one, but stock works fine for me.

And people are forgetting all about stock compressors vs these new units vendors are selling. A while back I thought my compressor was bad because it was making a squeaking noise. I read up on compressors and if memory serves correctly, the SD model number that was installed in our cars 30 years ago has a higher capacity pump than the newer units that are being sold by vendors. If you switch to a newer model number compressor you will have reduced cooling as well.

If you want the same high capacity compressor you have to go to eBay and look up the same model number you currently have. Btw, the squeaking noise ended up being due to an old belt. I spent $5 on a new belt and the problem was fixed.

[opethmike]

I can't believe that I am going to say this, but I am in full agreement with Steve.

When my R-12 system stopped working (slow leak in hose, near compressor), I had the system converted to R-134a. The system was flushed, then vacuumed, then filled with R-134a.

That was four years ago. Since then, I have to put in one can, once a year, and it runs great. I get mid-40s out of the vents.

[stevedmc]

I can't believe that I am going to say this, but I am in full agreement with Steve.

:TrainWreck:

[nullset]

I can't believe that I am going to say this, but I am in full agreement with Steve.

When my R-12 system stopped working (slow leak in hose, near compressor), I had the system converted to R-134a. The system was flushed, then vacuumed, then filled with R-134a.

That was four years ago. Since then, I have to put in one can, once a year, and it runs great. I get mid-40s out of the vents.

That's a pretty significant leak. I'd recommend fixing that. You're probably going to eventually end up with a bad oil/refrigerant mixture.

R-134a is a blend, and the portions of the blend escape in different proportions. It may continue to work, or it may eventually cause damage.

I'd strongly recommend tracking down and fixing your leak.

--buddy

[stevedmc]

That's a pretty significant leak. I'd recommend fixing that. You're probably going to eventually end up with a bad oil/refrigerant mixture.

R-134a is a blend, and the portions of the blend escape in different proportions. It may continue to work, or it may eventually cause damage.

I'd strongly recommend tracking down and fixing your leak.

--buddy

I believe he said he has been dealing with it for four years. $8 a year x 4 = $32 which is still a whole lot cheaper than fixing it the "right" way.

Edit: How is he going to get a bad oil/refrigerant mixture? I didn't think oil could evaporate from the compressor.

[nullset]

I believe he said he has been dealing with it for four years. $8 a year x 4 = $32 which is still a whole lot cheaper than fixing it the "right" way.

Until you end up with a dead compressor.

--buddy

[stevedmc]

Until you end up with a dead compressor.

--buddy

I've been expecting my 30 year old compressor to die since the day I got the car. When it fails I will simply replace it. When it does fail, I guarantee you it won't cost me $105 to refill the system. It will cost me about $24.

What boggles my mind is peoplehave come accustomed to checking tire pressure but almost never check AC pressure.

I can virtually guarantee my compressor isn't going to fail due to low refridgerant. When it fails, it is going to be due to it being 30+ years old.

[nullset]

I've been expecting my 30 year old compressor to die since the day I got the car. When it fails I will simply replace it. When it does fail, I guarantee you it won't cost me $105 to refill the system. It will cost me about $24.


Not for long. R-134a is going to be shortly banned, the same was R-12 was.



What boggles my mind is people willingly accept that people have come accustom to checking tire pressure but almost never check AC pressure.


AC should not leak. Pressure does not tell you how much refrigerant is in the system, only whether there is some liquid or not.



I can virtually guarantee my compressor isn't going to fail due to low refridgerant. When it fails, it is going to be due to it being 30+ years old.

It's more likely to fail due to too much or too little oil. Some of the cans have oil mixed in. Some don't. If there's too much oil, the compressor will struggle and fail. If there's too little…..

Either way, it's best to fix things right. I'll gladly evacuate and recharge AC for anyone that brings their car to Atlanta, whether it's R-12 or 134a.

The only way to determine how full the system is is to properly evacuate it and recharge it.

--buddy

[stevedmc]

For what its worth, this silly debate makes about as much sense as the lifetime coolant vs regular coolant thread.

Lifetime coolant is only lifetime until you have a breech in the system.

You could say that r12 is only worth the investment until you have a breech in the system.

[stevedmc]

Not for long. R-134a is going to be shortly banned, the same was R-12 was.

R-12 was never banned. I've got a can of it at home and fankly, if I want to spend the money I can buy a case of it anytime I want.

[nullset]

R-12 was never banned. I've got a can of it at home and fankly, if I want to spend the money I can buy a case of it anytime I want.

Manufacture of R-12 was banned in most of the world. It's still available, but the cans are not new.

There's also some that is available that has been recycled from old A/C units being retired, but again, it hasn't been manufactured in a LONG time.

R-12 is bad for the environment. R-12 in automotive A/C, though, wasn't really the problem. Using it in every damn spray bottle (hair spray, etc) was what actually caused the environmental damage.

--buddy

[stevedmc]

AC should not leak. Pressure does not tell you how much refrigerant is in the system, only whether there is some liquid or not.

Tires shouldn't leak either but they do. AC shouldn't leak either but on many cars it does.

Assuming you put a vacuum on the system and only filled it with refridgerant, then yes, pressure tells you whether or not you are loosing refridgerant. It might not tell you exactly how much, but any idiot can watch a scale while he adds refridgerant.

Btw, my fancy gauge has a window on it where I can actually see the refridgerant cycle.

[opethmike]

What Steve said. I've been running this way for thousands of miles of use every year, for four years. I know many people who run R-134a in their formerly R-12 systems, that converted in the same I did, and continue to run their systems without out any issue for years upon years.

I've had zero signs of any problems beyond needing to put in one stinking, small, and cheap can of R-134a every year. Whoopty doo.

I'm not going to spend hundreds of dollars and numerous hours to fix a supposedly "big" problem which isn't really a problem when I can spend 30 minutes and $10 a year to keep the system going, and providing excellent cooling.

[stevedmc]

It's more likely to fail due to too much or too little oil. Some of the cans have oil mixed in. Some don't. If there's too much oil, the compressor will struggle and fail. If there's too little…..

I never buy any of those gimmick products you are talking about. I said add r134a, not some gimmic arctic freeze product with miracle 50% colder synthetic crap that makes rainbows lead to pots of gold.

Only an idiot would try to top off refridgerant with a can containing oil. I may not have a brain, but I'm no idiot.


R-12 is bad for the environment.

Engine exhaust is bad for the environment. Why don't you sell your car and start riding a bus?

This bad for the environment crap bring up a whole other question.

What happens to the environment when you throw away your old rubber hoses and AC components? What polution is created in the manufacturing process of the new hoses. How many asian children had to give up their left pinky so you could have your cheap hoses. The list could go on an on.

Crap, everytime I hop on a flight (expecially international), I'm sure I'm contributing to far more polution than a year of my driving, or even a whole case of r134a. How come no one is bitching at me about that?

[David T]

You can find -12 for as little as $15 for a 14 oz can. If you have a leaky system and have to add refrigerant all the time then YES, it is much cheaper to run -134 but you should be fixing the leak. If you had a leaky tire, air is free (at most gas stations anyway) but you would still spend money and get it fixed! The main problem with a leaky system is they always seem to stop working on the hottest day of the year. You NEVER see A/C systems break in the wintertime! Why is that? Another good reason to fix a leaker. The oil gets carried out along with the gas. Eventually there is not enough oil to properly lubricate the compressor and it dies. Most people when they "shoot up" with a can of gas they NEVER think of adding any oil. If you have a bad leaker and air gets in, your head pressures start to go "through the roof" and you can't get enough refrigerant in because of all of the air. The best advice is to do it right for reliability and longevity of the parts. Cheaper over the long term.
David Teitelbaum

[opethmike]

Sure is a hell of a long term to cost less than $10 a year.

[stevedmc]

You can find -12 for as little as $15 for a 14 oz can. If you have a leaky system and have to add refrigerant all the time then YES, it is much cheaper to run -134 but you should be fixing the leak. If you had a leaky tire, air is free (at most gas stations anyway) but you would still spend money and get it fixed! The main problem with a leaky system is they always seem to stop working on the hottest day of the year. You NEVER see A/C systems break in the wintertime! Why is that? Another good reason to fix a leaker. The oil gets carried out along with the gas. Eventually there is not enough oil to properly lubricate the compressor and it dies. Most people when they "shoot up" with a can of gas they NEVER think of adding any oil. If you have a bad leaker and air gets in, your head pressures start to go "through the roof" and you can't get enough refrigerant in because of all of the air. The best advice is to do it right for reliability and longevity of the parts. Cheaper over the long term.
David Teitelbaum

Air isn't going to get in the system if you monitor it regularly. I didn't realize oil evaporates. I guess when my 30+ year old compressor finally dies you can blame it on oil.

[opethmike]

Air isn't going to get in the system if you monitor it regularly. I didn't realize oil evaporates. I guess when my 30+ year old compressor finally dies you can blame it on oil.

You didn't know that Steve? That's why gasoline is so expensive; all of the oil wells are drying up!

[stevedmc]

I still think this thread is way off topic. Someone asked, what is needed to convert to r134a?

So far I am the only person to ask if there is something wrong with his AC.

[sdg3205]

So far I am the only person to ask if there is something wrong with his AC.

Maybe, I don't know yet.

[stevedmc]

Maybe, I don't know yet.

Does the AC compressor cycle on? It will make a clicking noise when it cycyles on. Also, the center of the compressor will spin when it is on. If the center doesnt spin, but the belt moves, then it isn't kicking on.

If the compressor doesn't kick on you either have a bad compressor, or a leak somewhere in the system.

Testing the compressor is very simple. You will find one wire running from the compressor to the wiring harness. Disconnect the wire and run 12v directly to the wire connected to the compressor. You can use the positive terminal close to the coolant tank.

If you hear a clicking noise and the compressor kicks on, then chances are you have a leak somewhere in the system. Don't leave the compressor engaged too long because you will burn the compressor up.

If the compressor doesn't click at all and doesnt engage, then you will probably need to replace the compressor.

Let me know what is going on back there and I will do my best to help you, rather than just say "replace everything".

You are doing harm to the environment if you throw perfectly good components into the landfill.

[sdg3205]

Does the AC compressor cycle on? It will make a clicking noise when it cycyles on. Also, the center of the compressor will spin when it is on. If the center doesnt spin, but the belt moves, then it isn't kicking on.

If the compressor doesn't kick on you either have a bad compressor, or a leak somewhere in the system.

Testing the compressor is very simple. You will find one wire running from the compressor to the wiring harness. Disconnect the wire and run 12v directly to the wire connected to the compressor. You can use the positive terminal close to the coolant tank.

If you hear a clicking noise and the compressor kicks on, then chances are you have a leak somewhere in the system. Don't leave the compressor engaged too long because you will burn the compressor up.

If the compressor doesn't click at all and doesnt engage, then you will probably need to replace the compressor.

Let me know what is going on back there and I will do my best to help you, rather than just say "replace everything".

You are doing harm to the environment if you throw perfectly good components into the landfill.

Sorry Steve, I should have been more specific.

The system is bone dry. Always has been. Given it sat in the Arizona dessert for god knows how long, it could be filled with dust.

Evaporator looks good. I had it out when I replaced my heater core in the fall.

Long hose by steering column is shot. I didn't tether it well enough and it rubbed on the universal joint.

That's about all I know.

[dmc6960]

The system is bone dry. Always has been. Given it sat in the Arizona dessert for god knows how long, it could be filled with dust.

Evaporator looks good. I had it out when I replaced my heater core in the fall.

Long hose by steering column is shot. I didn't tether it well enough and it rubbed on the universal joint.

Then here is my quick and dirty recommendation...

Patch high pressure hose (duct tape should work). Flush system with mineral spirits. Remove and replace at least the two long hoses, optionally the short hose from condenser to evaporator. Replace the accumulator. Replace the orifice tube (optionally with a VOV I have one of these). Optionally if replacing all the hoses you could flush the condenser and evaporator directly and not mess with the whole system. Remove compressor and perform recommended Sanden conversion procedure. Replace all O-rings with new r-134a ones (since your breaking probably every connection anyways). Pressure check with DRY Nitrogen and verify no leaks in the compressor, condenser, and evaporator. Replace if needed. Add new oil to compressor, vacuum system, charge.

[stevedmc]

Sorry Steve, I should have been more specific.

The system is bone dry. Always has been. Given it sat in the Arizona dessert for god knows how long, it could be filled with dust.

Evaporator looks good. I had it out when I replaced my heater core in the fall.

Long hose by steering column is shot. I didn't tether it well enough and it rubbed on the universal joint.

That's about all I know.

Well, before you replace everything I would run down to harbor freight and invest in a AC vac, set of gauges, and a $5 r134a adapter.

Put the $5 adapter (you can get a fitting for just the low side at NAPA) on the low side. You can get another adapter for the high side if you choose but you will have to remove the shraider valve to install it. Don't remove the valve until you are 100% certain there is no pressure in the system.

You can do basic testing using just the low side (left side of compressor). Hook your gauge up to the installed r134a adapter and see if there is any pressure. If it is bone dry there shouldn't be any pressure.

Once you have verified the system is empty, hook your vacuum up to your set of gauges, and let it pull a vacuum for 30 or 45 minutes. If memory serves me correctly you will see the gauge drop well below 0. Maybe -20 lbs (i could be completely wrong on the exact number but it will be in the negative).

Now, turn the knob on the gauges that restricts the vacuum from sucking through the set of gauges, and turn off the vacuum. Let the car sit 30 minutes and see if the gauge is still in the same negative position. If it is, let the car sit and hour and check it. If it is still in the same spot let it sit overnight.

If the gauge doesn't move after sitting overnight, then chances are you can get by with what you have. If it does move, then you have a really bad leak that will need to be corrected.

This simple test won't cost you any refridgerant but will cost you some basic tools. You can pickup the gauges for about $40 when they are on sale and you can get the compressor

I think I got my gauges for $50 but I have seen them on sale for as little as $40.
http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html

I think I got my compressor on sale for somewhere between $80 and $100.
http://www.harborfreight.com/a-c-manifold-gauge-set-92649.html

These are tools you purchase one time and use over and over again. The AC in my mom's car quit working a few days ago. Guess who's tools I used to diagnose the problem and who's tools i will be using to replace the AC compressor.

[stevedmc]

Then here is my quick and dirty recommendation...

Patch high pressure hose (duct tape should work). Flush system with mineral spirits. Remove and replace at least the two long hoses, optionally the short hose from condenser to evaporator. Replace the accumulator. Replace the orifice tube (optionally with a VOV I have one of these). Optionally if replacing all the hoses you could flush the condenser and evaporator directly and not mess with the whole system. Remove compressor and perform recommended Sanden conversion procedure. Replace all O-rings with new r-134a ones (since your breaking probably every connection anyways). Pressure check with DRY Nitrogen and verify no leaks in the compressor, condenser, and evaporator. Replace if needed. Add new oil to compressor, vacuum system, charge.

Shouldn't he check for leaks before he starts doing all of this stuff?

[dmc6960]

Shouldn't he check for leaks before he starts doing all of this stuff?

Remember I'm one of those who spends over $1000 replacing everything when I had one component go bad (compressor).

I have a hard time, a REALLY hard time, not suggesting replacing all the hoses since one is for sure bad. I also have a REALLY hard time not suggesting replacing the accumulator, orifice tube, and all o-rings. Since under my logic it all needs to be done anyways, and those are statistically the most likely spots for a leak, when all is said and done everything should be fine with the other components.

[DMCMW Dave]

Without getting into the whole debate, I'd really recommend that you avoid the cheap conversion fittings you get at the local parts store. They are aluminum and will wear out after you use them once or twice. Then they leak.

Get the good steel ones from a better parts store, they don't really cost any more. They have integral valves rather than a push-through. Remove the shrader valves from the car side and install the conversion fittings. They will (usually) work with the original shraders in place, but charge much slower and will often jam and cause leaks.

[stevedmc]

Get the good steel ones from a better parts store, they don't really cost any more.

Amen. I think Bill has gone through a few of the cheap ones already. I have a high pressure one, purchased from NAPA that I only paid $5 for. It has yet to be installed because I don't want to evacuate the system.

The cheap ones actually cost more. My low pressure valve came in a kit from walmart that cost about $12. None of the high pressure ones in the kit fit my car so I ended up going to NAPA anyway.

[Henrik]

I read up on compressors and if memory serves correctly, the SD model number that was installed in our cars 30 years ago has a higher capacity pump than the newer units that are being sold by vendors. If you switch to a newer model number compressor you will have reduced cooling as well.

If you want the same high capacity compressor you have to go to eBay and look up the same model number you currently have.

Not true. The Sanden SD-510 compressor that came with the D is/was a 5 piston, 161 cc per rev. wobble plate compressor. It was the backbone of the trucking industry for decades and has served the industry well. When R134a came on line 20 years ago comparative durability testing showed us that the 510 didn't stand a chance against the competition . This was under highly controlled and extreme conditions: 440 psig head pressure, 40 psig suction pressure, 6000 rpm and fast cycling. In real life conditions high pressure is usually associated with low speed (poor cooling at idle and stop-and-go driving) and low pressure with high speed (good cooling at highway driving). High pressure AND high speed AND cycling is a compressor killer. The 510 granaded way before the competition (Denso, Zexel and all other Sanden compressor). The successor was the Sanden SD7H15 compressor (known as the SD-709 during the R-12 era). The 7H15 is a 155 cc per rev 7 cylinder wobble plate compressor specifically beefed up to handle R134a. True, the physical displacement is slightly less than the 510 but its volumetric efficiency is higher so in actuality it is pushing more refrigerant per revolution. And again, it is much more durable, and also less noisy due to its internal spiral gears.

For my D's R134a conversion I replaced my old 510 with an SD7H15 compressor. If you spec it correctly you can make it a direct drop in replacement: The SD-510 for the D is to be exact an SD510Q8494. This fully defines the mounting style, clutch style, clutch diam, clutch offset, cylinder head and fittings. The exact SD7H15 drop-in equivalent is an SD7H15QC4708. This model will bolt right on your D without any modifications. Even the little bullet connector for the clutch wire will plug right in. Most people won't even see the difference. (Side note: Not all distributors carry all models so if they're nice they will assemble one based on your needs. A/C Parts Warehouse (acparts.com) did this for me way back in 2006....)

[Chris4099]

Very interesting. How does the SD5H14 compare to the SD7H15? I see the SD5H14 has a 138cc displacement and is 5 bore, but is it otherwise the same design? That's the one for sale at specialtauto.com and is the one I have installed. Works fine here in Oregon and I do like how between it and the low current fans, I can't even feel it cycle (I use an indicator light inside to monitor cycling).

I probably won't have to replace mine for a few more decades, but it's good to know there are different options out there.

[Henrik]

Very interesting. How does the SD5H14 compare to the SD7H15? I see the SD5H14 has a 138cc displacement and is 5 bore, but is it otherwise the same design? That's the one for sale at specialtauto.com and is the one I have installed. Works fine here in Oregon and I do like how between it and the low current fans, I can't even feel it cycle (I use an indicator light inside to monitor cycling).

I probably won't have to replace mine for a few more decades, but it's good to know there are different options out there.

The SD5 is on older design (5 vs 7 cyl; straight vs. helical internal gears etc) but in terms of durability it is on par with the 7H15 and performance wise the difference is very little. If you go to the Performance section of Sanden's website:

http://www.sanden.com/index.php?tag=U5H0AMX7Q

and look at the performance curve for both compressors you can see that the refrigerating capacity for the two are actually very close. I personnally prefer the 7H15 because it's quieter but on the other hand, because of its slightly higher capacity, the 7H15 may cause more clutch cycling during lighter conditions (i.e. like in Oregon) and condenser fan cycling during high heat conditions so - it might be a toss-up.

The limiting factor in most car applications is the condenser which a lot of people have pointed out in this forum. R134a naturally runs higher pressures so one thing that is very important for people who are converting, is to use a lesser amount of R134a than R-12. I did a so called Charge Determination on my D and came up with the new, lesser charge amount (at which point it blew ice chunks BTW); I don't have that number here at work but I can post it later tonight. If you put in the same amount of R134a as you did R-12 you will lose performance and also sacrifice durability over the long haul. This may be a reason why some people have the perception that R134a is not as good as R-12 - but it is.

[stevedmc]

Not true. The Sanden SD-510 compressor that came with the D is/was a 5 piston, 161 cc per rev. wobble plate compressor.

When I was considering replacing my compressor someone message me and told me not to do it. I think it was on the old forum so I have no way of finding the post/message.

I've got zero proof but I was told by someone that the SD510 does a better job at idle than the newer model numbers being sold by vendors. This person told me he noticed a decrease in cooling at idle after swapping compressors.

"A plane like a Boeing 747 uses approximately 1 gallon of fuel (about 4 liters) every second."
http://science.howstuffworks.com/transport/flight/modern/question192.htm

"Steve's Delorean AC leaks one or two cans of r134a a year".
http://www.dmctalk.org

Which do you think is causing more harm to the planet? The only real valid reason for air travel is for transporting goods. The rest of the people are just flying to business meetings and Disney World.

[jawn101]

"A plane like a Boeing 747 uses approximately 1 gallon of fuel (about 4 liters) every second."
http://science.howstuffworks.com/transport/flight/modern/question192.htm

"Steve's Delorean AC leaks one or two cans of r134a a year".
http://www.dmctalk.org

Which do you think is causing more harm to the planet? The only real valid reason for air travel is for transporting goods. The rest of the people are just flying to business meetings and Disney World.

But the 747 is operating within design parameters. Your leaky A/C system is, well.. leaky. It shouldn't be losing anything and is thus environmentally detrimental by your choice, not by design.

Drawing the comparison between air travel being frivolous and an A/C system requiring frequent recharges is also a bit specious, as I doubt very much that you'd die if the A/C system was completely evacuated or removed from your car. You have A/C because you want to. People fly places because they want to. If no one did any of those things, certainly there'd be less environmental impact. But of course it will never just stop, and the goal should instead be to make our own activities as minimally impactful as possible. The plane flies just as well whether it's full of people on vacation, full of cargo, or empty and has to go anyway because it's a scheduled route and just needs to be at its next hop. Similarly, you claim your A/C works just as well whether it's leaking or not. Does that mean it's *desirable* to operate under those sub-optimal conditions? Or is it simply *possible*?

This is a discussion that could go for days so I'll not say more, as it wasn't OP's original intent to spark a debate on the topic.

[Bitsyncmaster]

With the price of R-134a going up, you will want to get that leak fixed to save money. You could get a can for less then $5 a year or two ago. Now your lucky to find one for $10.

[stevedmc]

With the price of R-134a going up, you will want to get that leak fixed to save money. You could get a can for less then $5 a year or two ago. Now your lucky to find one for $10.

I can buy it any day I want for $8 a can.


People fly places because they want to. If no one did any of those things, certainly there'd be less environmental impact.

And I'm driving around with a leak in my AC because I want to.

It also amused me when I went to Antarctica. Most people on the ship, including the expedition crew, was all about saving the planet and not disturbing the wildlife. Suprisingly they were willing to take my money to cruise a big diesel ship which puffed tons of black smoke into the atmoshere as we crossed the drake passage on our way to antarctica.

Its just a big double standard. If people really cared about my car hurting the environment, they would simply live on a farm and never go anywhere. In reality, everyone hurts the environment whether he or she chooses to acknolege it.

[Chris4099]

You're still missing the point, but then you also clearly just don't care. Does this mean if we meet at DCS, I can punch you in the stomach? After all, by your line of thinking, far worse things are happening out there like murder and therefore why bother with the smaller stuff like assault and simple battery. :) It doesn't matter that I'm in full control of my own actions that effect others.

[stevedmc]

Does this mean if we meet at DCS, I can punch you in the stomach?

You can but I might "fart in your general direction."


http://www.youtube.com/watch?v=FWBUl7oT9sA

[stevedmc]

I can't remember if the comment I am about to make is off topic of not but here goes.

Another reason to convert to r134a is convenience. Right now my car is at a collision center because someone chose to drive it into brick wall. The damage was minor but I need my fascia painted, radiator/shroud replaced, and possibly need the AC condensor repalced.

Today I was on the phone with one of the guys at the shop. We were talking about the condensor and I mentioned to him that my system has been converted to r134a. I could hear a sigh of relief over the phone and then he mentioned being happy to hear that since they don't have equipment to handle r12.

The reality is there are less and less shops equiped to handle r12. If I was still running r12 I wouldn't be able to get this collision center to touch my AC and I would be stuck hunting for a place just to do AC work. If a shop isn't equiped to handle r12 they will not be able to evacuate your system to convert it to r134a.

You can save yourself a lot of headache by just converting to r134a yourself.

[David T]

While it is true most shops will no longer handle R-12, mainly because it is so expensive but also because there is very little call for it since most cars on the road today no longer use it. Just because it is not convenient is not really a good reason to convert. If you are in a large city, if you look, you should be able to find someone who still handles R-12 or a drop-in substitute. If you told the collision shop you were still on R-12 he would have had to find someone to service the A/C or talk you into converting. Converting will cost more than staying with -12 even though -134 is cheaper. That is if it is converted correctly. Once the insurance company hears that the job will cost more because they "upgraded" you to -134 they would not pay for it. They only have to pay to "make you whole", not improve you. Lastly, going to -134, even doing the conversion correctly, wil reduce your cooling capacity about 10%. You won't notice it unless it is really hot but that is exactly when you need it the most!
David Teitelbaum

[stevedmc]

While it is true most shops will no longer handle R-12, mainly because it is so expensive but also because there is very little call for it since most cars on the road today no longer use it. Just because it is not convenient is not really a good reason to convert. If you are in a large city, if you look, you should be able to find someone who still handles R-12 or a drop-in substitute. If you told the collision shop you were still on R-12 he would have had to find someone to service the A/C or talk you into converting. Converting will cost more than staying with -12 even though -134 is cheaper. That is if it is converted correctly. Once the insurance company hears that the job will cost more because they "upgraded" you to -134 they would not pay for it. They only have to pay to "make you whole", not improve you. Lastly, going to -134, even doing the conversion correctly, wil reduce your cooling capacity about 10%. You won't notice it unless it is really hot but that is exactly when you need it the most!
David Teitelbaum

You obviously haven't lived what you are preaching. I was in that situation over a year ago and it was nothing like the fairly tale you just described.

[David T]

I live in the NYC area and there are plenty of shops that will still handle R-12. It is recycled stuff and it is expensive but available. Virgin -12 is still available on the Internet (Ebay). Most shops will offer R-414 or other drop-in replacement refrigerants. I do my own work and I try to use -12 but also have used -414. I always have said it is best if you can stay with -12 for the most cooling capacity and saves you all of the trouble of converting. It is a lot of work to change all of the parts and seals and get all of the old oil out of the system. If you have a guilty conscience about using -12 for environmental reasons and it makes you sleep better at night, go for the conversion. Be aware -134 is ALSO being phased out for exactly the same reasons -12 was phased out for.
David Teitelbaum

[stevedmc]

I live in the NYC area and there are plenty of shops that will still handle R-12. It is recycled stuff and it is expensive but available. Virgin -12 is still available on the Internet (Ebay). Most shops will offer R-414 or other drop-in replacement refrigerants. I do my own work and I try to use -12 but also have used -414. I always have said it is best if you can stay with -12 for the most cooling capacity and saves you all of the trouble of converting. It is a lot of work to change all of the parts and seals and get all of the old oil out of the system. If you have a guilty conscience about using -12 for environmental reasons and it makes you sleep better at night, go for the conversion. Be aware -134 is ALSO being phased out for exactly the same reasons -12 was phased out for.
David Teitelbaum

I'm sure there is a mechanic every 50 feet down the street in Manhattan. There are several mechanics in Baton Rouge but I'm sure not nearly as many as where you live. When my r12 system was compromised about 18 months ago I was only able to locate one shop in Baton Rouge that still had equipment for r12. They didn't want to touch my "exotic" car for fear of screwing something up. I would have just serviced the system myself but I was doing an insurance claim instead of doing the work on my own.

My comment was, "a good reason to convert is convenience". It can also be cheaper to convert to r134a than to keep r12. The only additional expense is a $5 adapter you need to put on the low side but the $5 expense is easily recouped because r134a is $8-$10 a can and r134a is about $35 a can.

I honestly wouldn't trust eBay r12 for several reasons. There have been instances where people on eBay have lied about selling r12 and have been either selling blends or propane, and also it is illegal to ship refrigerant unless you follow the guidelines for shipping hazardous materials. Most of the eBay sellers are breaking the law because they ship the cheapest way possible and they illegally ship to people who are not licensed to install the stuff.

Incidentally, I have a can of r12 I was thinking of putting on eBay until I read about the guidelines for shipping. There is no way I am going to go through the red tape to ship the item the right way and there is no way I am going to ship the item illegally. If anyone wants to buy a can of r12 from me at DCS I will bring it along and sell it to you in person.

I am licensed to buy r12 yet I've chosen to go the r134a route. I survived just fine last summer. Did I mention I live in the south and the temperature gets as high as 110 degrees?

People can brag and say r12 is better all day long but the reality is r134a works just fine. If there was that big of a difference there would be advertisements all over the south from companies offering to convert r134a systems to r12. I have yet to see an advertisement for this during any of our 110+ degree summers.

[content22207]

The idea that R134 conversions are inherently difficult or expensive is incorrect. I am sure some conversions do in fact turn out to be difficult and expensive (for example, owners who go wrenching on 30 year old components and end up damaging the thin wall tubing from which they are made). If you leave major components and hoses in place, an R134 conversion can be fast, simple, and inexpensive.

1) R12 uses mineral oil, therefore your best bet is to use mineral spirits (paint thinner) as your flushing agent. If you have access to compressed air, flush the system backwards (low side towards high side) to push any contaminants away from the orifice tube rather than into it. I have run as much as a whole gallon of paint thinner through a system when converting.

2) Ester oil is compatible with any residual mineral oil. PAG is not. Always use Ester in a converted system.

3) All parts houses rent vacuum pumps now. When I first started doing my own A/C work many years ago they did not, so I used engine vacuum as a poor man's alternative. Now, there is no reason not to rent a proper vacuum pump. Always pull a vacuum before recharging the system.

4) When recharging the system, stay away from cans of freon that include oil. Not only are most of them PAG, but each can contains at least 2 oz of oil (the really big ones contain 4-6 oz). A typical A/C compressor only holds about 6 oz of oil altogether. If you overfill your system with oil, it will puddle in the condensor and especially in the evaporator, preventing them from working properly. If you need to add oil, take the compressor off and pour it in the back (Sanden compressors also have an oil fill plug in the top). When in doubt, pour the oil from your compressor into a measuring cup to see how much is in it.

Speaking of which, where in the world did the idea that condensors, evaporators, hoses, etc "need" oil ever come from? Some oil does indeed get picked up by the freon and carried throughout the system, but most of it stays in the compressor where it belongs. There are no moving parts in a condensor or evaporator to lubricate. Measure the oil in your compressor. If it's OK, you're OK.

5) Sanden compressors are probably the most common automotive compressor out there. They are extremely plentiful on eBay (be aware that some of them are Made in China knockoffs, but for the right price even a Made in China compressor that dies prematurely could be more cost effective than a genuine Sanden unit). Also watch the bolt pattern on the back -- some of them use 7 bolts instead of 5 (you will most likely need to swap over your back). It is far easier, and most likely cheaper, to simply replace a compressor that is leaking at the pulley shaft. I was able to score an SD5H14 brand new in the box for $125 a couple of years ago. Note that compressors are typically shipped dry (you need to add oil before firing them up).

6) Stay away from R12 to R134 quick connect adapters that do not include their own schrader valve. Most of them have only a spring loaded pin inside that presses on the original schrader valve, which is liable to bend and even wedge against the original valve. For the same price NAPA sells a heavy duty steel adapter that includes its own valve (unscrew the original valve before threading on the NAPA adapter). To the best of my knowledge Autozone/Advance/O'Reilly's/Pep Boys do not sell adapters with integrated valves. It's a good idea to replace the schrader valve even on an unconverted system -- they don't last forever (you wouldn't go driving around on 30 year old valve stems).

7) If your system is working normally, all functions can be performed through the low side port (vacuuming, charging, pressure monitoring, etc). Look closely at this pic and you will notice my car does not have a high side adapter installed:
http://sphotos.xx.fbcdn.net/hphotos-ash4/301468_266950483350209_100001057778755_815307_1870 748139_n.jpg
(That's my previous compressor BTW: A SD-510 I also picked up off eBay new in the box -- I am on my third compressor now, counting the SD-508 the car came with, due to shaft seal leakage. I also had to replace my low side pressure switch with an Autozone xRef because the original one rusted and leaked as well).

The complaint that R134 is 10% less efficient in an R12 system holds no merit on a 100 degree day, when 36 degrees from the vents feels just as good as 32 degrees.

Anyway, my car is still running the same hoses, condensor, evaporator, and accumulator it left Dunmurry with more than 30 years ago. I am not going to risk damaging my evaporator by wrenching on its tubing (note that the accumulator attaches directly to the evaporator). I lose about 1 -2 can of freon per year -- $20 per year at today's prices. The argument that I am damaging the O Zone is specious at best -- what do you think is in every single can of Dustoff people go spraying on their computer keyboards every day? R134 used to be the propellant in asthma inhalers (changed a couple of years ago, much to asthmatics' dismay -- the new propellant doesn't work as well). R134 is also used in food processing, and in manufacturing processes. Some sort of freon is used in spray paint (ever notice how the can gets cold just before the paint runs out?).

Replacing every single component in your A/C system is certainly an option, but it is not necessary.

Bill Robertson
#5939

[Bitsyncmaster]

Good to hear Bill is back.

I've always had new compressors come shipped filled with oil. Most likely PAG since that is what Sanden recommends. So you would need to dump that oil out and maybe a quick flush if your using ester.

[Morpheus]

Since I'm doing a frame-off restoration, I will be replacing the entire AC system and converting to R134. I figure the cost will be amortized over many years of cool driving.

My grandfather always told me "There are 2 ways of doing things: 'right' and 'again'."
;)

[dvonk]

R134 used to be the propellant in asthma inhalers (changed a couple of years ago, much to asthmatics' dismay -- the new propellant doesn't work as well).

a random irrelevant side note; i was working as a pharmacy technician in 2007 when they started switching Metered Dose Inhaler propellant (http://www.sciencedaily.com/releases/2007/03/070329075220.htm) from CFC (chloroflurocarbon) to HFA (hydrofluoroalkane). we had many people bringing them back and complaining that they were less effective. when we would randomly get a few of the 'old' kind from the warehouse, they were like gold. eventually, the supply ran out... the asthmatics just had to deal with it.

i least i could deflect the blame to the government because i literally had nothing to do with it.

[David T]

If you are converting there are a few things that should be done at a minimum. We will assume the system is at least clean inside, coils are clean on the outside, all of the fans work and actuators function as they should. All three hoses should be replaced. The dryer/accumulator should be replaced. The condenser and evaporator should be flushed. The compressor should be drained, flushed, and refilled with oil. The service fittings must be changed. The system leak-tested and vacuumed before being filled with -134. The low pressure switch should be adjusted. A label MUST be attached indicating the type and amount of refrigerant. You WILL be running at much higher pressures on the low side and the high side, and the BTU content of -134 is not as high as -12. You also cannot put as much -134 in so there is no way the system can have as much capacity as the original -12 did. We can argue if it is noticeable and how much it is but you WILL have diminished capacity. Running a "leaker" is bad no matter if you are wasting -12 or -134.
David Teitelbaum

[stevedmc]

If you are converting there are a few things that should be done at a minimum. We will assume the system is at least clean inside, coils are clean on the outside, all of the fans work and actuators function as they should. All three hoses should be replaced. The dryer/accumulator should be replaced. The condenser and evaporator should be flushed. The compressor should be drained, flushed, and refilled with oil. The service fittings must be changed. The system leak-tested and vacuumed before being filled with -134. The low pressure switch should be adjusted. A label MUST be attached indicating the type and amount of refrigerant. You WILL be running at much higher pressures on the low side and the high side, and the BTU content of -134 is not as high as -12. You also cannot put as much -134 in so there is no way the system can have as much capacity as the original -12 did. We can argue if it is noticeable and how much it is but you WILL have diminished capacity. Running a "leaker" is bad no matter if you are wasting -12 or -134.
David Teitelbaum

So let me get this straight. To convert to r134a a person must replace their hoses and then check for leaks?

Call me stupid, but it makes more sense to check the hoses for leaks before deciding to replace them. If there are no leaks there isn't much sense in replacing the hoses.

[David T]

After replacing any component you ALWAYS check for leaks. I am assuming you have not replaced any parts (including the hoses) recently prior to converting. By replacing the hoses you will be replacing just about all of the seals. You should not use the black Buna N rubber "O" rings with -134. Because you will be running much higher pressures with -134, using the original hoses doesn't make any sense. If they haven't blown yet in 30 years they soon will with -134! New hoses are made out of better materials and will not leak as much and will last longer. Even if you are not converting you should not be running on original hoses at this point in time.
David Teitelbaum

[stevedmc]

After replacing any component you ALWAYS check for leaks. I am assuming you have not replaced any parts (including the hoses) recently prior to converting. By replacing the hoses you will be replacing just about all of the seals. You should not use the black Buna N rubber "O" rings with -134. Because you will be running much higher pressures with -134, using the original hoses doesn't make any sense. If they haven't blown yet in 30 years they soon will with -134! New hoses are made out of better materials and will not leak as much and will last longer. Even if you are not converting you should not be running on original hoses at this point in time.
David Teitelbaum

I don't have any other 30 year old cars but the hoses on my 18 year old Geo Metro have zero leaks and the system was opened up for the first time a year ago to replace a bad compressor.

I still maintain that if the hoses aren't leaking they don't need to be replaced. You are just asking for problems if you start wrenching on 30 year old connections. Ask Farrar. He has been without AC for about 2 years because someone convinced him it would be a good idea to change all of his hoses. Unscrewing a 30 year old rusted connection isn't as simple as it sounds.

[David T]

You are correct, unscrewing a 30 year old connection must be done carefully with the proper tools. It CAN be done. No reason not to do it or have it done by someone who can do it. As for 30 year old hoses, if they are not leaking now (and I strongly doubt that they are NOT leaking) they soon will. At least they will if a) the system is filled with freon and b) you are actually running the A/C. Drive a Delorean around for a while when it's hot without A/C and you will want those hoses replaced ASAP!
David Teitelbaum

[stevedmc]

You are correct, unscrewing a 30 year old connection must be done carefully with the proper tools. It CAN be done. No reason not to do it or have it done by someone who can do it. As for 30 year old hoses, if they are not leaking now (and I strongly doubt that they are NOT leaking) they soon will. At least they will if a) the system is filled with freon and b) you are actually running the A/C. Drive a Delorean around for a while when it's hot without A/C and you will want those hoses replaced ASAP!
David Teitelbaum


Once again, my Geo Metro isn't exactly 30 years old but its hoses are leak free. Its only 18 years old, but I have a feeling you would be saying the same thing about delorean AC hoses if these cars were only 18 years old.

[DMCMW Dave]

You are correct, unscrewing a 30 year old connection must be done carefully with the proper tools. It CAN be done.

You must not see many salt-belt driver cars. There are quite a few actually that can't.

[David T]

If it sticks force it. If it breaks it needed replacing anyway!
Murphy's Law.

I HAVE seen many very rusty cars. Even so, with the right tools it is rare that I can't undo fittings. I have flare nut wrenches and ratcheting wrenches. The hardest ones are the ones where the aluminum goes to steel. They seem to corrode the most and are usually the ones that leak. Probably because of the corrosion. When all else fails I cut the hoses, remove the parts and use heat to undo the connections. I am sure you have seen more and probably worse than I have. In any case, if you have a bad hose or a leaking connection you have to do what you have to do to fix it. If that means replacing parts, then that is what you have to do.
David Teitelbaum

[stevedmc]

If it sticks force it. If it breaks it needed replacing anyway!
Murphy's Law.

So just replace the whole car.

[David T]

See the "I'm done with this car" thread.
Don't ask how many times I have felt that way! When I reach that point it is time for a break! A little time away form the problem and you can approach it again maybe in a different direction.
David Teitelbaum

[dmc6960]

So just replace the whole car.

:hysterical:

I may not laugh at every joke you make, but this one absolutely made my day.

[sean]

See the "I'm done with this car" thread.
Don't ask how many times I have felt that way! When I reach that point it is time for a break! A little time away form the problem and you can approach it again maybe in a different direction.
David Teitelbaum

Great advice! I PM'd him the same thing a few minutes ago.


:hysterical:

I may not laugh at every joke you make, but this one absolutely made my day.

Great, now he's really gonna turn it on.

[Ron]

You seriously think he was joking?
:rolleyes1:

[stevedmc]

See the "I'm done with this car" thread.

I believe that was an email. Once again you are wrong.


You seriously think he was joking?
:rolleyes1:

Are you talking about me or David?

[Chris4099]

I just had to go back and correct a few things from Bill's post...


The argument that I am damaging the O Zone is specious at best --
Nobody is saying that. R-134a doesn't damage the O-zone. The issue is it's 1500 times worse then CO2 when it comes to global warming. It's insulating properties and half-life are pretty well defined, not specious at all.


what do you think is in every single can of Dustoff people go spraying on their computer keyboards every day?

You must have forgotten our conversation years ago when I told you this exact same thing. Standard off the shelf canned air now uses Difluoroethane (R-152a). R-134a hasn't been used in years in that application! Next you'll be saying they still use asbestos in new household insulation. :biggrin:


Some sort of freon is used in spray paint (ever notice how the can gets cold just before the paint runs out?).

You can use all sorts of propellents, but you won't find R-134a as any of them. It's going away for a reason. While not as nasty as R-12, it's still bad and there are better ones out there which have been phased in. As for it getting cold, that has to do with basic physics. Compress a gas, you get heat. Decompress gas, it absorbs heat.

[dvonk]

...As for it getting cold, that has to do with basic physics. Compress a gas, you get heat. Decompress gas, it absorbs heat.

+1. for more info, you can read about Enthalpy of Vaporization (http://en.wikipedia.org/wiki/Enthalpy_of_vaporization)!

i think i get a little to excited about science. :biggrin:

[jawn101]

i think i get a little to excited about science. :biggrin:

Nonsense. No such thing.

[dvonk]

i think i get a little to excited about science. :biggrin:

haha, apparently too excited to bother with correct spelling. :lol:

[DMCVegas]

The idea that R134 conversions are inherently difficult or expensive is incorrect. I am sure some conversions do in fact turn out to be difficult and expensive (for example, owners who go wrenching on 30 year old components and end up damaging the thin wall tubing from which they are made). If you leave major components and hoses in place, an R134 conversion can be fast, simple, and inexpensive.



The complaint that R134 is 10% less efficient in an R12 system holds no merit on a 100 degree day, when 36 degrees from the vents feels just as good as 32 degrees.

It is indeed a rare occasion, but...

:werd:

That's all absolutely correct on these two points. The other consideration is that with R-134a you can also install a VOV to ensure a constant flow of refrigerant during idle, but as well should also adjust the Low Pressure Switch too in order to accommodate the viscosity of the refrigerant.

I honestly don't know where the quote about a 10% diminished cooling capacity comes from. I don't know if that's related to the specific amount of BTUs that R134a can absorb when compared to R12, or if it has to do with overall system performance due to the viscosity of R134a when used in a system that is not configured to accommodate it.

[David T]

The diminished capacity is do to the reduced amount of refrigerant, the lower BTU capacity of the refrigerant, the higher pressures, and the size of the evap and cond coils. A VOV would probably help a lot, it would allow you to put a little more refrigerant in without the evap coil freezing over. The system in the Delorean was not engineered to use -134.
David Teitelbaum

[stevedmc]

The diminished capacity is do to the reduced amount of refrigerant, the lower BTU capacity of the refrigerant, the higher pressures, and the size of the evap and cond coils. A VOV would probably help a lot, it would allow you to put a little more refrigerant in without the evap coil freezing over. The system in the Delorean was not engineered to use -134.
David Teitelbaum

My car functions fine with stock components and r134a. I get 43 degree vent temperatures when cruising on the highway.

For what its worth though, I must mention something. A reduced capacity is not necessarily a bad thing. Last summer I was bragging to a coworker about my 43 degree vent temperature. He told me that was pathetic and his chevy truck (a 2009 model I believe) could cool even better than that. We got in his car, put the same thermometer in one of his center vents and his temperature read 60 degrees. Suprisingly we weren't hot at all on that summer day.

There is one thing I noticed that was different between my old car and his modern truck. Window tint! His truck came from the factory with a nice dark window tint on all of the windows (except windshield of course). I supposed his car was better insulated as well.

So my argument would be that you can fuss all you want about a reduced capacity but there are systems out there that have far less capacity than our silly little cars (running r134a btw) that seem to work just fine.

[jawn101]

This is an interesting discussion. Can someone describe what the principle behind the VOV actually is? When I did my 134 conversion (yes, new hoses, compressor, o-rings, low pressure switch, dryer, oil, etc) I opted to skip the VOV as I had heard that its benefits were dubious. It was one of the very first systems I repaired when I got the car and I hadn't yet learned to take single opinions with a grain of salt.

So, what would the difference between the VOV and the standard oriface tube actually be?

[dmc6960]

Its variable.

But in all seriousness, I did a bunch of research on them when I did my conversion, using a VOV. The idea is that it opens up more for low load conditions, reducing head pressure and allowing better cooling at low speeds.

I get 36º-40º vent temps with my VOV enabled new-component r134a system. With my old R-12 system I got 34º-38º. A difference, yes, but only from a technical standpoint. I intend to eventually increase efficiency even more with a parallel flow condenser.

[stevedmc]

I get 36º-40º vent temps with my VOV enabled new-component r134a system.

Thats awesome.

[sean]

So opinions on running without any orifice tube?

[Bitsyncmaster]

The VOV valve can not bend (if your pipe is bent) and still work. So if you install one make sure the pipe is strait. My was bent and I had to go back to the standard orifice.

[Henrik]

So opinions on running without any orifice tube?

You mean, no orifice tube at all? You have to have something that drops the pressure from high pressure to low pressure or there won't be any cooling at all...

[sean]

You mean, no orifice tube at all? You have to have something that drops the pressure from high pressure to low pressure or there won't be any cooling at all...

I just seem to remember someone suggesting once that they omitted he Otube.

[stevedmc]

The system in the Delorean was not engineered to use -134.



Gene Kranz: I don't care about what anything was DESIGNED to do, I care about what it CAN do. (Apollo 13)
http://www.imdb.com/character/ch0005117/quotes

[dmc6960]

The idea is that it opens up more for low load conditions, reducing head pressure and allowing better cooling at low speeds.

I would like to correct what I had posted from before. I was running off of memory there, and got things reversed. Here is an excellent summary from a website selling VOVs...


The Smart VOV (variable orifice valve) uses system pressure and refrigerant flow to move a metering piston relative to a fixed opening in the sleeve. The piston movement is resisted by an attached spring.

When idling at high ambient temperatures, the piston shifts to a smaller metering area similar to a TXV. This compensates for the reduced compressor output and increases the cooling performance. The Smart VOV also has a unique re-open feature which reduces compressor pressure for severe idle conditions.

At highway speeds, the Smart VOV operates on a large orifice. The net result is better performance than a TXV without the complexity or reliability concerns.

Unlike a TXV, which has constantly moving parts and small internal clearances, the Smart VOV is stationary during most operating conditions and has large internal clearances. Its low friction floating design insures smooth operation and extremely long life.

This is from here...
http://www.acsource.com/smartvov-highperformanceorificetubes.aspx

I believe this has the result of actually increasing head pressure at idle. All the more reason for new hoses and a damn good condenser/radiator/fan combination.

[David T]

When designing a cooling system one of the first, most important things is to know what the heat load is so you can size your cooling system. The Delorean seems to have a bigger heat load than most cars because the front window is so flat and large in comparison to the internal volume. Simply stated, a Delorean gets more heat from the sun concentrated inside than a comparable car of similar size. Tinting will certainly go a long way in reducing heat load. So will insulation in the headliner. and the firewall. You could also insulate the suction line from the evaporator to the compressor and the dryer/accumulator. All of these little things add up and will help keep the car cooler. On many cars I see the door actually start to frost. If the duct comes apart all of the cold air blows on the outer door skin and makes the door cold, not the interior. I also see many times where the rubber boot that connects the center ducts is not set right and you have large leakage basically keeping the radio cold. Bottom line, no matter if you have -12 or -134, if the cooling system is not set up right and operating correctly you will not have all of the capacity you could have. There is also a BIG hole up under the driver's side dash that has a chunk of foam stuck in it. The foam deteriorates and you get a large heat vent!
David Teitelbaum

[DMCMW Dave]

I just seem to remember someone suggesting once that they omitted he Otube.

I had a car come in the shop once with a very oddly functioning system. Not much cooling. Pressures were all wrong (very low high side pressure with a full charge), and we finally figured out that the last guy who worked on it left the orifice tube out.

[David T]

You MUST have something (an orifice tube, a VOV, something!) to separate the high side and the low side. The orifice tube is not sensitive to ambient temperature, evap pressure ANYTHING. It is designed and sized to a specific operating parameter and that's it. The only adjustment with it is to play with the amount of refrigerant and the setting on the low pressure switch. Not a very versatile method to control the flooding of the evap coil. Most cars have a more sophisticated control system, at least an expansion valve with superheat. Getting the right VOV you wouldn't have to cycle the A/C to keep it from freezing so if it can run more it can cool more. That would give you some of the cooling capacity you would lose if you convert to -134. The "trick" is to get the right VOV. Alternately the system could be modified to an adjustable expansion valve. You also need some valving to keep the evap coil from going below atmospheric and freezing. BTW, that is the reason the heater valve is open during A/C. When you run MAX the heater valve is closed and you take the chance of freezing the evap coil AND the heater core, especially if you do not have enough anti-freeze protection. How's THAT, freezing the heater core in the summer time! One of the reasons you need to run 50/50 water and anti-freeze summer AND winter.
David Teitelbaum

[stevedmc]

For what its worth, I went to Big Lots last night and picked up some more r134a at $8 a can. I believe I have a stockpile of about 20 cans of the stuff.

[jawn101]

For what its worth, I went to Big Lots last night and picked up some more r134a at $8 a can. I believe I have a stockpile of about 20 cans of the stuff.

Would be great to stock up, if CA didn't tack on a time-limited $10 per can core charge :angry:

[Bitsyncmaster]

My wall mart it's about $10 a can.

[stevedmc]

My wall mart it's about $10 a can.

I've got a few $10 cans from Walmart too. At that price it is still a good deal but $8 for 12 ounces at Big Lots is a steal right now.

Right now that stuff starts out at $15 a can at AutoZone and the price will go up when the new stuff becomes standard.

I have no immediate need for the 20 cans I have, but I have a feeling it will be easy to get rid of them at $15 a can in the future if I ever decide to sell them.

[stevedmc]

Would be great to stock up, if CA didn't tack on a time-limited $10 per can core charge :angry:

I would offer to ship you some empty cans but its probably a safety hazard to ship even an empty one.

[Bitsyncmaster]

I have no immediate need for the 20 cans I have, but I have a feeling it will be easy to get rid of them at $15 a can in the future if I ever decide to sell them.

I bought a bunch back when they were $5 a can. That was when my AC was leaking but now it seems fixed. So I'll hold onto them and maybe get $20 can in a few years :evilgrin:

[stevedmc]

I bought a bunch back when they were $5 a can. That was when my AC was leaking but now it seems fixed. So I'll hold onto them and maybe get $20 can in a few years :evilgrin:

I'm tempted to bring my 20 cans to DCS and pop holes in each can in front of a few people on this forum.

9697I was wrong. I have 24 cans.

[Chris4099]

I've got 3 cans, so I'm set for the next 20 years (would be 30 but there is my DD too).

[stevedmc]

I've got 3 cans, so I'm set for the next 20 years (would be 30 but there is my DD too).

So you don't think you will be purchasing any old cars over the next 20 years?

[sdg3205]

Decision: I'm staying R-12.

[Chris4099]

So you don't think you will be purchasing any old cars over the next 20 years?

My D is the oldest car I ever plan to own. I got it for nostalgia and style. When it comes to daily drivers for transportation, cars are like any other engineered product where they get refined and improved with time. So I prefer to take advantage of those improvements when I want a new DD. Now that I think about it, with r-134a going away, my next DD may not even use it. So those cans may just be used for my D only.


Decision: I'm staying R-12.
Cool. If you can, use ester oil. That way if you later decide to convert, its just a simple swap of refrigerants as ester is compatible with both types. I even got the old style connections w/ r-134a adapters so I could switch myself if I wanted to. Even though I'm happy with the performance, its nice to know I have options.

[sdg3205]

Im hoping to install the needed components myself then have Toby charge the system.

[sdg3205]

After replacing my damaged components I went to dmcnw today for a recharge since no one in my area works with r12.

My ac now blows around 44 degrees. Epic win. Glad I stuck with it. Total cost to bring my r12 system back from the dead was around $600. That includes everything from refrigerant to the orifice tube.

[stevedmc]

After replacing my damaged components I went to dmcnw today for a recharge since no one in my area works with r12.

My ac now blows around 44 degrees. Epic win. Glad I stuck with it. Total cost to bring my r12 system back from the dead was around $600. That includes everything from refrigerant to the orifice tube.



My car functions fine with stock components and r134a. I get 43 degree vent temperatures when cruising on the highway.

Is your AC system still stock or are you using a different compressor? The reason I ask is I get 43 degree vent temperatures with r134a at highway speeds. Everything in my system is stock, including the hoses and a NOS condenser. Did you measure your temp from the center vents and did you measure it while idling or cruising? Your vent temp should be at least a few degrees better than mine.

[sdg3205]

That was at idle. John measured it with a digital meter. Stock compressor. I noticed on the way home it got colder.

I'll get one of those meat thermometers and see how low she can go at some point.

[stevedmc]

That was at idle. John measured it with a digital meter. Stock compressor. I noticed on the way home it got colder.

I'll get one of those meat thermometers and see how low she can go at some point.

Awesome. I bet you are getting somewhere between 35-38 degrees on the highway.

[Jimmycxc]

I know r-12 is still available to buy, but would something like this work when it becomes more scarce?

http://www.ebay.com/itm/Freeze-12-Refrigerant-R12-AC-Replacement-12oz-Cans-/330726752575?hash=item4d00d9c13f&item=330726752575&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr

[sdg3205]

I know r-12 is still available to buy, but would something like this work when it becomes more scarce?

http://www.ebay.com/itm/Freeze-12-Refrigerant-R12-AC-Replacement-12oz-Cans-/330726752575?hash=item4d00d9c13f&item=330726752575&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr

Excellent question.

IIRC, a lot of the R-12 "substitutes" are propane based, which some claim to be dangerous. RedTek is an example of this. On one hand, it seems to work well in the short term, but long term you might see compromise from mixing oils or refrigerants.

I've found a wide array of opinions on the subject. Sure, propane is explosive, but so is the giant tank of gas under your radio.

In the end, I simply decided to fix it once and do it right and have it tested, vacuumed and recharged properly.

[David T]

R-12 is going to be around for a long time unless it is made illegal to recycle. R-414 is a good substitute. It is what is called a "blended" refrigerant, it is made up of fractions of several different refrigerants. Without an MSDS sheet on Freeze 12 you just don't know what is in it. R-12 will just keep getting more and more expensive but it will be available for a long time. By the time you can't get -12 you won't be able to get -134 either. Just another way the Government is forcing everyone to get rid of their old stuff and replace it with newer stuff. I would worry more about the gasoline.
David Teitelbaum




I know r-12 is still available to buy, but would something like this work when it becomes more scarce?

http://www.ebay.com/itm/Freeze-12-Refrigerant-R12-AC-Replacement-12oz-Cans-/330726752575?hash=item4d00d9c13f&item=330726752575&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr

[stevedmc]

I know r-12 is still available to buy, but would something like this work when it becomes more scarce?

http://www.ebay.com/itm/Freeze-12-Refrigerant-R12-AC-Replacement-12oz-Cans-/330726752575?hash=item4d00d9c13f&item=330726752575&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr

Its easier, cheaper, and better to just convert to r134a. The only real reason to use a blend is to top off a leaking R12 system when R12 is not available.

[sdg3205]

Awesome. I bet you are getting somewhere between 35-38 degrees on the highway.

The other cool thing (no pun intended) about having working A/C is that the fans are always on, so you can sit in traffic and keep the engine and cabin cool without watching the meter creep up and down, which used to make me sweat all the time anyway.

I know it sounds elementary, but its something you just dont think about when you DONT have A/C. I used to run the heater with the doors open to help keep the temperature down.

[DMCVegas]

I've found a wide array of opinions on the subject. Sure, propane is explosive, but so is the giant tank of gas under your radio.

Yeah, but your tank is designed to be sealed off. The concern with Hydrocarbon-based refrigerants is if they develop a leak and then flood the passenger compartment with gas mixed with oxygen. Best case scenario is headaches & fatigue, descending into asphyxiation and possible cremation like Gus Grissom if that gas ignites.

[David T]

If you don't like the idea of using flammable gasses like Propane you can always use Ammonia. Makes a GREAT refrigerant if you can handle it's corrosive properties. Too bad it's also toxic. As for R-12 being so safe, it was invented by the Germans before WW II as a precursor to Phosgene gas which is what they really wanted. Only later did they realize it had good properties to make it what was called a "Safety" refrigerant since it was not as toxic as Ammonia which is what was in wide use at the time. Just FYI the way they make Phosgene gas is to pass R-12 through a flame. Now how do you feel about the safety of R-12, the "Safe" refrigerant! Dow made a LOT of money with it! It was used in just about every car, window air conditioner, and refrigerator for a lot of years. They also used it as a propellant in aerosol cans, it was so cheap.
David Teitelbaum




Yeah, but your tank is designed to be sealed off. The concern with Hydrocarbon-based refrigerants is if they develop a leak and then flood the passenger compartment with gas mixed with oxygen. Best case scenario is headaches & fatigue, descending into asphyxiation and possible cremation like Gus Grissom if that gas ignites.

[DMCVegas]

If you don't like the idea of using flammable gasses like Propane you can always use Ammonia. Makes a GREAT refrigerant if you can handle it's corrosive properties. Too bad it's also toxic. As for R-12 being so safe, it was invented by the Germans before WW II as a precursor to Phosgene gas which is what they really wanted. Only later did they realize it had good properties to make it what was called a "Safety" refrigerant since it was not as toxic as Ammonia which is what was in wide use at the time. Just FYI the way they make Phosgene gas is to pass R-12 through a flame. Now how do you feel about the safety of R-12, the "Safe" refrigerant! Dow made a LOT of money with it! It was used in just about every car, window air conditioner, and refrigerator for a lot of years. They also used it as a propellant in aerosol cans, it was so cheap.
David Teitelbaum

Well if you burn R134a you get mustard gas. The key of course is the ignition temperature. Propane, Butane, and other hydrocarbon derivatives used in alternative refrigerants will ignite at much lower temperatures like say a cigarette. R134a for example needs to be heated to over 1,300°F before it will ignite. The temperature for R12 is so high that the MSDS sheet for it lists it as N/A. Ammonia is of course one of the first refrigerants too, but can't be used because of safety concerns if the system leaks serious injury including death from inhalation can occur.

HC based refrigerants are indeed very efficient at the jobs that they do, but aren't ideal. The best bet really is to either stick with R12 or convert over to R134a.

[stevedmc]

Phosgene gas

Phosgene gas is bad. I work at a chemical site that uses it to manufacture other chemicals. Every once in a while we have a phosgene leak and it can be a little scarey. Fortunately, there has been only one phosgene related death at my site.

Basically, if you breath the stuff you will die within two days. It causes the lungs to fill up with fluid until you drown and die. There is no treatment to prevent death from breathing the stuff in.

When working in the site I am required to carry a escape respirator (which is rated for clorine and not phosgene incidentally) to use in the event of a leak. Suposedly it is good enough just to get you to safety.

Steve's escape respirator use procedure is as follows:
1. Hear the alarm
2. Take respirator out of pouch
3. Throw respirator as high in the air as you can
4. Run
5. If you can hear the respirator when it hits the ground you didn't run fast enough


10761

[dvonk]

yikes, talk about a job hazard...

[stevedmc]

yikes, talk about a job hazard...

It's safer than driving a Delorean. Today on my way to work a cop got out of his car, flexed like the incredible hulk, and then yelled something at me while pointing at the ground. Weird stuff like that makes driving a Delorean a lot more hazardous than a phosgene leak.

[Bitsyncmaster]

There was a lot of talk about R134a on the DML. Price for those 12 oz. cans is climbing every time I look at it. So I went and bought a 30 lb. tank on EBAY for $139 + $9.99 shipping. It just arrived (took a few days) via FedEx. It's a well packed brand new bottle so I'm happy to have it even thought my AC seems to be leak free.

I just got a new home heat pump that runs on R410a. My house has two heat pumps and the old one needs a charge about once a year. Guess what R22 is going for these days......about $60 lb. I see they are selling an alternative for R22 which is a blended freon at much less cost. I may order a tank of that to postpone the replacement of my second unit. The replacement was $3900.

[stevedmc]

There was a lot of talk about R134a on the DML. Price for those 12 oz. cans is climbing every time I look at it. So I went and bought a 30 lb. tank on EBAY for $139 + $9.99 shipping. It just arrived (took a few days) via FedEx. It's a well packed brand new bottle so I'm happy to have it even thought my AC seems to be leak free.

Man I'm stupid. Thats a much better deal than the 36 12oz cans I picked up the other day at $6.97 (after tax) per can. On the possitive note, I should be able to get $15/can for them in less than 5 years.

[Dangermouse]

I just got a new home heat pump that runs on R410a. My house has two heat pumps and the old one needs a charge about once a year. Guess what R22 is going for these days......about $60 lb. I see they are selling an alternative for R22 which is a blended freon at much less cost. I may order a tank of that to postpone the replacement of my second unit. The replacement was $3900.

I just had the AC guy out to look at one of my units. Charged me $110 for "some" R22- how he knew how much it was I dont know. Interestingly he found that the shut off valves at the condenser were not tight and that may have been where it was leaking. Sorry, OT.

[ccurzio]

Man I'm stupid.

Quoted for posterity.

[sadeeky]

R-12 molecules a a bit bigger than R-134A molecules.
The A/C hoses in our cars are for R-12.
Using R-134A in those hoses will slowly loose refrigerant due to those molecules escaping from the system through the hose wall.

It's not something you have to worry about.
Have the system checked each year for sufficient refrigerant and you will be fine.

What you need to do:
- Replace all O-rings in the system
- Replace the orifice (in the pipe to the A/C evaporator)
- Replace the accumulator (dryer)
- If in doubt: replace low and high pressure switch (so you don't have to go in there again)
- drain the compressor oil
And after re-assembling of the system:
- refill compressor with ester oil (150 grams)
- have the system pressurized with nitrogen (for about 2-24 hours)
- no leaks? then vacuumize the system
- fill the system with R-134A (approx. 850 grams) and have fluor added too (allows easy checking for leaks using special lamps and glasses).
- have the A/C temp checked and if not right, adjust the low pressure switch half a turn depending on the outcome

Have a cool system :)


So doing all this does it make the AC blow cooler than the original stock AC?

[jawn101]

So doing all this does it make the AC blow cooler than the original stock AC?

Eh. Not really, I'd say. If you're lucky it will be as good or not much worse. R12 was arguably a better (if less environmentally sound) refrigerant.

[WelmoedJ]

So doing all this does it make the AC blow cooler than the original stock AC?

No, it only makes it reliable.
Keeping the original hoses still loose some refrigerant (as mentioned due to molecule size).
If you want to stop refrigerant loss, you'll have to echange the original hoses for the ones suitable for R134A.

I agree with jawn101 that R134A may not reach the 'cool' temps of R12.

However it may well (almost) match the same temps of R12 but you will need to adjust the proper pressure switch.
My car with R134A maintains a steady 5° Celsius (41° F) on A/C High.
Have to check the refrigerant every 2 years (old R12 hoses) for losses.

[Chris4099]

Keep in mind the R-12 system is overbuilt for the size of our cars. When it's cycling, that means it's not running at 100% capacity (perfectly normal to cycle unless it's extremely hot outside). In most cases, R-134a will simply cycle less and still cool just as much (when converted properly). In my case, since I'm not in a very hot environment, my compressor isn't as powerful as the stock one. This means virtually no cycling. It also means it doesn't put nearly as much load on the engine too. When driving around, I can't feel it cycle like I would with the stock R-12 system. The compressor not cycling as much also means it should last longer.

[dmc6960]

So doing all this does it make the AC blow cooler than the original stock AC?

Well, if your looking to make your R12 system "colder than original", you're out of luck. HOWEVER, if your R12 system is not performing optimally right now, and that is your reference base, then yes you can improve it with a proper R134a conversion. The following is a quote of mine from near the beginning of this thread. It is my justification for replacing (nearly) every component when I did my system, now 7 years ago. I'll follow with a few more notes on optimizing performance at the bottom...


It is up to the individual to decide what they want to install. But with a 31 year old AC system, usually it needs a lot...

Compressor, single biggest "wear" item for an AC system. Fast moving parts, many different seals. I had over 90k miles on my car when I did my AC. My compressor clutch was failing, and the compressor itself was leaking. No brainer.

Condenser, second biggest "wear" item, though most people dont realize it. This part, being in the very front of the car, takes the brunt of road debris and insects, etc. Good airflow is ESSENTIAL here. Replacing it naturally freshens up its available airflow increasing its capacity, weather being replaced with a NOS or generic replacement. For the best performance you want the largest one which will fit and a "Parallel Flow" design for ultimate r134a performance. I dont believe anybody currently sells a compatible parallel flow condenser perfectly sized up. I will be helping someone else this year do a complete AC conversion and we'll be ordering a properly sized unit from a non-DeLorean vendor and adapting it to fit perfectly. I may also go back and replace my new (2006) condenser with one of these once we know the exact one to get.

Accumulator - A MUST replace during a conversion, no matter what. And a part that should usually be replaced when opening up any system for extended service.

Hoses - The original hoses just do not hold back the r134a. If you choose not to replace the hoses with new barrier hoses, you choose to refill with refrigerant every year. The person I'm assisting this year has previously converted to 134a replacing as little as possible at the time. Has had to add refrigerant every year. No other leaks in the system. He is completely unsatisfied which is why we are replacing everything now.

Cooling fans/radiator - While not directly part of the AC system, they play an extremely important role. You need good fans which can pull a lot of air. Dont fall for fans which are just advertised as "low current". They wont pull as much air, and that is the most important thing the fans do. Get the ones Toby at DMCNW has. Also consider your radiator, which if plugged with debris will not allow optimal airflow through the condenser. Also if original with plastic endcaps now is the best time to switch it out.

Evaporator - You gotta be careful here. These can easily spring a leak if the lines get twisted while trying to remove the hoses/accumulator. This could be justification to not replace much, but since the accumulator is the single most important thing to replace anyways, and you need to remove the high pressure line to get to the orifice tube, well justification lost then. Even if you do not replace the evaporator, it still should be cleaned out. A surprisingly high amount of debris gets in there. Your hands and a creative vacuum extension can work really good through the blow motor opening. However for the ultimate clean you need to remove it, which is of course a LOT of work, and at that point many people justify getting a new one anyways.

That was all my justification. Your mileage may vary.

With that said, here are a few more notes I've thought of in the year since I wrote that...

I never mentioned the orifice tube above. I used a VAV, which has worked well for me. Other people have had problems inserting them into the evaporator (less flexible) or had performance issues with them. If nothing else just replace it with a new standard orifice tube.

John Hervey currently DOES sell the proper-sized parallel-flow condenser, based on measurements from Billy in this thread...
http://dmctalk.org/showthread.php?5004-Misplaced-my-2-O-rings-for-the-water-pipe-Y-pipe
Specifically post 17 (http://dmctalk.org/showthread.php?5004-Misplaced-my-2-O-rings-for-the-water-pipe-Y-pipe&p=71225&viewfull=1#post71225), 19 (http://dmctalk.org/showthread.php?5004-Misplaced-my-2-O-rings-for-the-water-pipe-Y-pipe&p=71230&viewfull=1#post71230), and 22 (http://dmctalk.org/showthread.php?5004-Misplaced-my-2-O-rings-for-the-water-pipe-Y-pipe&p=71238&viewfull=1#post71238).
Alternately, it is also available here (https://www.ackits.com/pc/12-0440C/Parallel/12-0440C+-+FSHE+PF+Condenser+%2812+X+27%29), but you may need to fabricate your own mounts (or look at these pictures (http://dmctalk.org/showthread.php?5004-Misplaced-my-2-O-rings-for-the-water-pipe-Y-pipe&p=71225&viewfull=1#post71225) to see how John Hervey did it)

Tinted windows and windshield will greatly reduce the heating affect from the sun, which is the single largest contributor to cabin heating and discomfort due to heating. Especially since your in FL. You could have a high flow 35º AC blowing in your face. Your face will be cold, but the rest of your body will still be hot and sweaty. I suggest 3M Crystalline tint (http://solutions.3m.com/wps/portal/3M/en_US/Window_Film/Solutions/Markets-Products/Automotive/Crystalline_Automotive_Films/) for the side windows. Its the highest quality tint available from anywhere today. Unfortunately its only available through professional installers, but is well worth it. And in a car like the DeLorean, using only the best is a valid option since it'll be around a long time. The windshield is not legal to add tint I think in any state without a medial reason. However thanks to DMCH listening to their customers (yes, they really do!), we now have a factory UV/IR tinted windshield option. It may be double the cost of a standard replacement, but I'd say its worth it in reduced interior wear in addition to the added AC comfort it will gain you. Imaging having a dash or binnacle that wont crack again? $500 right there.

Finally, if you really want to get COLD, and I seriously mean COLD, then modify your seats to add power ventilation cooling. There are a few cheapie-style conversion kits (http://www.sportsimportsltd.com/seatvenheats.html) you can add to your seats. There are also a few speed/specialty shops (http://www.championseatheaters.com/content/home.html) which can do this. I did it myself using new perforated seat covers from DMCH, some high powered blower fans, and custom foam work.
http://dmctalk.org/showthread.php?3473-Heated-AND-Cooled-Seats

Overall, in most cases just getting the AC system to perform properly is enough for most people. By properly, that means that its both cooling as it should, and blowing enough airflow as it should. The next best thing to do after that would be tinting the side windows. You want to go above and beyond that, you can, but it'll cost you.

[David T]

The A/C HAS to cycle for a couple of reasons. The biggest one being under the right conditions the Evap coil can freeze. By turning off the compressor (reducing the capacity temporarily) the coil defrosts. On other cars of the era they had complicated valving to prevent freezing the coil. Added to the expense and complexity. Cycling was a much more elegant engineering solution. The other big reason for cycling is to reduce the load on the electrical system. If you run the cooling fans continuously you will overheat the wiring and overload the alternator. Because the Molecules of R-12 are larger, (higher atomic weight) R-12 has a higher heat transfer rate than the same amount of R-134. That's why you need a little more and the pressures are higher with -134. Another reason that the condenser coil is sized larger in -134 systems and the compressor is made to run at higher pressures (higher temperatures on the high side). Bottom lining this, if the system leaks, fix the leaks. Replace the hoses and try to stay with R-12. Even though R-12 is expensive, it is not so expensive as to be unaffordable as long as the system isn't leaking. Another BIG thing to fix is the ductwork inside the doors. If it is leaking you lose a LOT of cold air in there. On one car it actually frosted a spot on the door on the outside! Also make sure the boot on the center vents is on properly or you are just cooling the radio!
David Teitelbaum

[dmc6960]

Repeating something over and over again does not make it true. While most of what Dave wrote is fairly accurate, I would like to dispute two points...


If you run the cooling fans continuously you will overheat the wiring and overload the alternator.

This is not true. A system such as the cooling fans would NEVER be designed at less than 100% duty cycle. There are many situations where a car will need this system to be running continuously. Yes there were initial weaknesses in the cooling fan circuit, but those are known and can now be mitigated. In 2001 I ran my stock cooling fan circuit (with 3-position jumper and uprated breaker) for an ENTIRE season at 100% duty cycle due to a faulty otterstat from John Hervey. There was no overheating of my stock wiring or my stock alternator.


Another reason that the condenser coil is sized larger in -134

This while technically true can be compensated with in our cars by running a "parallel-flow" condenser, and combining with high-flow fans like Toby's at DMCNW. This makes up for (and them some) the technical performance loss of r134a.

[David T]

I have it on no less an authority than Rob Grady who worked with Bob B to create the Zilla line of products. The first one was Fanzilla because of the design problems with the cooling fan circuit. The brass connectors which are attached to the ends of the wires are not even appropriately sized to handle the current continuously. In any circuit sized to handle 20 amps (as an example) it cannot handle more than 75% continuously. That means any load over 15 amps for more than 20 minutes is too much. The circuit CAN handle even more than 20 amps but the more you use over 15 the shorter the period you can do that. To add to all of this, as the fan motors get older they tend to draw more power and there is also corrosion at each connection. All of this means a wiring system that was inadequate to begin with is overloaded even more. I personally have seen a fan fail bypass go up in smoke as another owner was driving. You run the cooling fans continuously at your peril (you also wear them out faster). Although it is working for you it cannot be recommended for the fleet. As for the size of the evap coil, I didn't say you couldn't overcome that problem, I only mention it as a problem. Same for the compressor, you can put a different compressor on. In fact, there is a bolt-on replacement for the compressor. At this point even -134 is being phased out so maybe you should look ahead to the next replacement. Or just stay with R-12? The timing on this post is a little early, we are probably a month from A/C season when all of the A/C posts will start up again. At least for us in the northern areas of the US.
David Teitelbaum

[Bitsyncmaster]

We know the OEM fans draw close to 40 amps (20 amps each). I do think the design (wiring and components) for OEM fans is marginal for reliable operation but if you drive in the summer than your fans are going to run 100 % of the time anyway in city driving. Running the AC will reduce your engine cooling and even if your AC cycles the otterstat is going to keep them running anyway.

Most of us have replaced those OEM fans to get better reliability. With about half the power the wiring and components will have no problems with clean connections.

[Ron]

In any circuit sized to handle 20 amps (as an example) it cannot handle more than 75% continuously. That means any load over 15 amps for more than 20 minutes is too much.Conversely, that means the circuit was designed ("sized") for 15 Amps...maybe less.

[DMCMW Dave]

We know the OEM fans draw close to 40 amps (20 amps each). .

I have never measured OEM fans to pull that much current.

[Bitsyncmaster]

I have never measured OEM fans to pull that much current.

It is dependent on the cars voltage but with 14.5 volts on my OEM fans hit 20 amps each. Now probably the voltage drops of the wiring will keep that voltage at the fans less than 14.5 volts.

Many people have tested the current without the engine running. Big difference. Also big difference with the fans mounted with the AC and radiator blocking the air flow.

Here is a test I did with just the radiator blocking the air flow.

[David T]

When any motor starts it can draw between 2-3 times it's running current. You can actually feel it in the gas pedal when the fans come on, especially if you don't have something like a Fanzilla that will sequence them so they both don't hit the electrical system together all at once. There will also be a big difference between the current draw with the car moving and the car stopped. The forward motion of the car through the air will reduce the amount of power the fan motors draw. I agree changing the fan motors to the newer pancake style is a good upgrade but not everyone will do it because of the expense. An old fan motor can draw a LOT of current, the grease gets dried out and becomes more like glue than grease. And with worn bearings and worn brushes it can draw upwards of 2 X it's normal amount even after it gets going. The whole electrical circuit for the cooling fans IMHO is woefully inadequate. It is one of the Delorean's weakest points. The two weakest systems in a Delorean are the cooling system and the electrical system and here is where they both come together!
David Teitelbaum