R-12

[DMC3165]

Well it's that time of year again and my A/C isn't working that well. Everything apperars to be working and the compressor is cycling normally but I think the A/C system may need a charge. Previously in cooler weather the A/C compressor would kick on and off every minute or two but in the warmer weather the clutch would engage almost 100% of the time. Now even on the hot days it seems to kick on and off and it really isn't getting all that cool leaving me to think it needs a charge. The A/C system was last serviced about 3 years ago.

The downside to this is I never converted to R-134 and R-12 is almost impossible to find these days. This may be a long shot but are there any safely compatable gases that I can use with R-12? Something that I can get and put in myself? Has anyone here found or used anything like this? what about converting to R-134? How much does it cost and what's involved? Price and time are always king with me because I use the car daily.

[Jonathan]

I have had good luck with the Red-Tek12 product. It won't solve bigger picture problems that a given A/C system might have, but it's not $1,000s either. The kit with the gauges and connectors, and two refill cans was about $55. Replacement cans for future seasons might be $20 a piece. Depending on where you live, what the summer weather is like, and how much you use your car, this can be a decent solution. I live in a place where it doesn't get that ridiculously warm or humid for too many days. I also don't drive my car all that often, and not for day to day errands or going to work. I was okay spending $55 to get my A/C working, but not $1,000s. Others in different circumstances may feel differently.

[David T]

You can still find R-12 on E-Bay. Although it is expensive, you should not need very much, 1 can would be enough.
David Teitelbaum

[Michael]

I refuse to convert to a less effective freon just to satisfy the EPA. Also a lot of mechanics will suggest converting to 134 not because its better for you, but because its easier for them. It's getting hard to even find a shop that still has a r12 machine anymore. If one pops up around here cheap I'm buying it. I have had great success with Freeze 12. It's been in my DeLorean for 3 years now, and I used it in my old Accord for about 5 years. Never had a problem.

[LordFly]

You're kinda on the wrong side of the state, but if you're gonna be near the border, in Canada we sell cans of R12 at just about every auto parts store for about $10-$15 per can :)

[DMCMW Dave]

You're kinda on the wrong side of the state, but if you're gonna be near the border, in Canada we sell cans of R12 at just about every auto parts store for about $10-$15 per can :)

That's not R12. It's Red-Tek12. A hydrocarbon refrigerant i.e. propane.

Real R12 is illegal in Canada. It's even supposed to be drained from cars before you import them.

[DMC3165]

That's not R12. It's Red-Tek12. A hydrocarbon refrigerant i.e. propane.

Real R12 is illegal in Canada. It's even supposed to be drained from cars before you import them.

This scares me a little. I've heard of stuff like this that are flammable refrigerants. Obviously if something goes wrong you'll have an explosive mixture running throughout your HVAC system. Are these products safe to use? It doesn't seem like they would be.

[Ron]

I was going to suggest Freeze 12 but it looks like it has went up in price quite a bit.

http://www.amazon.com/Freeze-12-Refrigerant-R-12-Replacement-Can/dp/B002EQKP2Q/ref=sr_1_2?s=automotive&ie=UTF8&qid=1369453158&sr=1-2&keywords=freeze+12

$3,751.00 12oz Can. :jawdrop:

[kajcienski]

I was told the R12 produced a colder temp... Is that nuts or did I hear this correct? I still have R12 and 2 years later after last charge, feels like a freezer. Is it something us R12 people should stock up on?

[DMCMW Dave]

I was told the R12 produced a colder temp... Is that nuts or did I hear this correct? I still have R12 and 2 years later after last charge, feels like a freezer. Is it something us R12 people should stock up on?

You can find it on eBay

[Bitsyncmaster]

You can find it on eBay

Yes they still make R-12 in Mexico. You could get it on EBAY, not sure how long that will last. Then you need to find the can tap for the flat sealed cans.

[David T]

You are correct to be concerned about what is being sold as a 'replacement" for R-12. Some of the stuff is mixed with Propane and is VERY flammable. It is also illegal to be used but that doesn't stop some people from selling it. R-414 is a good replacement, but ANY replacement, including -134, is not as efficient as R-12 in a system designed to use R-12 as a refrigerant. That means you will lose some cooling capacity. In some cases not enough to notice but if it is REALLY hot and humid it will take longer to cool and it will not cool as much. Bottom-lining this, as long as you can still get -12 you should try to get it and use it and fix your leaks so you don't have to always top it off.
David Teitelbaum

[Nicholas R]

I bought several mexican cans of R-12 on ebay several years ago. I remember specifically that I could NOT use paypal to pay for it because it is in paypals terms of use that you cannot use it to buy things like that. I had to make an account with gunpal.com (essentially a paypal that allows you to pay for everything including guns and r-12) in order to pay for the order. Not sure if that's still the case. I believe this was back before ebay bought paypal so maybe now anything that's on ebay can be paid for with paypal.

Most sellers though say you must be EPA certified to buy. Whether or not they verify is just a gamble I guess. They did not ask back when I bought it.

From what I understand though it's pretty damn easy to be certified. Cliff S. her in town is certified and he said he just went online, took the test, probably paid a little money (not sure whether or not its free) and they sent him the card. Here's where you get certified: http://www.epatest.com/

[DMC3165]

While going over my A/C system yesterday. I noticed the compressor was cutting out as the engine speed increases. I'm pretty sure that's a sign of low pressure. But I'm wondering if maybe the switch went bad? Is there a safe way of checking the low (and high) pressure switches without damaging the system?

[DMC5180]

Are you still running R-12? Cycling more as the rpm increases is normal to a certain extent. If the clutch cycles ON/OFF at idle you are probably low on refrigerant. The best way to check is with a manifold gauge set. Those are getting hard to come by for R-12 systems. (in the US that is). You could call around to local garages to see if anyone still services R-12 in your area.

[DMC3165]

Are you still running R-12? Cycling more as the rpm increases is normal to a certain extent. If the clutch cycles ON/OFF at idle you are probably low on refrigerant. The best way to check is with a manifold gauge set. Those are getting hard to come by for R-12 systems. (in the US that is). You could call around to local garages to see if anyone still services R-12 in your area.

Yes I am still running R-12. I frequently bring my car to PJ Grady's for service because he is very close to me and I may ask him to look at it next time 3165 is there. But he is only one man and I'm trying to sort out as many things as possible on my own without bothering the guy every few weeks. 3165 has been fairly trouble free outside of basic maintenance for a few years now. But lately it's been giving me a little grief and in addition there's always the issue of money. So if I'll try to fix almost anything myself if I think I can handle it.

[kings1527]

Are you still running R-12? Cycling more as the rpm increases is normal to a certain extent. If the clutch cycles ON/OFF at idle you are probably low on refrigerant.

I was told that it was normal to have the compressor cycle for 8 sec or so and then off for 2-3 sec all while at idle. Is that not correct?

How should the compressor be cycling during idle and at higher RPM?

I think I'm freezing my evaporator since my compressor seems to constantly be cycling. I think I need to adjust my low pressure switch so it'll cut out.

[DMC5180]

I run 134 so I cannot say for 100% sure that the system would act the same. When I have a properly charged system the compressor will run continuously @ idle when the Fan speed is on 3-4. Increasing RPM to 1000 or Higher will make the system start cycling. You can force it to cycle @ idle by running on fan speed 1.

[dmc6960]

I think I'm freezing my evaporator since my compressor seems to constantly be cycling. I think I need to adjust my low pressure switch so it'll cut out.

Never adjust the low pressure switch without watching the gauges, knowing the actual charge, and monitoring the temperatures.

Also, you technically ARE "cutting out" the compressor currently. Thats the definition of cycling. Dont worry about freezing your compressor unless you start to notice a loss of airflow after a little bit of time on the same settings.

[David T]

Actually the compressor cycling on and off is what keeps the evap coil from freezing over. There are two ways to know if you have the proper amount of refrigerant. The first way is to only put in a weighed amount. The second and less accurate way is to measure the high and low side pressures, the ambient air temperature and the cabin temperature.
David Teitelbaum

[kings1527]

Never adjust the low pressure switch without watching the gauges, knowing the actual charge, and monitoring the temperatures.

Also, you technically ARE "cutting out" the compressor currently. Thats the definition of cycling. Dont worry about freezing your compressor unless you start to notice a loss of airflow after a little bit of time on the same settings.

Yes, I'll have to hook up my gauges to know for sure what I'm looking at but at idle my compressor is constantly engaged while at idle. I think I used the wrong terminology; it's not cycling on and off, it's constantly engaged. Should it be doing that at idle?

I'm not losing airflow but what I notice after running it for awhile is my temperature creep up. I start off at around 38-40 degrees but after it's been running for awhile it'll go up to 45-50 and then I'll hear and feel what I think is the compressor doing its thing and it'll take the temps down to the real low 40's, but then it'll cutout and my temps will crawl back up until the compressor engages for about 5 seconds or so, and then everything repeats itself. I'm wondering if my system froze up and that's why it's doing that. The entire cycle of temps up -> compressor engaging -> temps down -> compressor cutout -> temps back up all takes about 10 seconds or so for all of that. The ambient temp was about 65 degrees while in the shade as I was figuring all this out, maybe roughly low 70's while I was driving around with the AC on and assessing the system.


Actually the compressor cycling on and off is what keeps the evap coil from freezing over. There are two ways to know if you have the proper amount of refrigerant. The first way is to only put in a weighed amount. The second and less accurate way is to measure the high and low side pressures, the ambient air temperature and the cabin temperature.
David Teitelbaum

I'm 100% sure I have the correct amount of R12 in the system. I digitally weighed my container as I filled it and I'm around 2.2-2.3 lbs of R12 and 100% without any leaks. I need to get my gauges on and see where I'm at with my pressures when all of this is happening.

[TTait]

I refuse to convert to a less effective freon just to satisfy the EPA. Also a lot of mechanics will suggest converting to 134 not because its better for you, but because its easier for them. It's getting hard to even find a shop that still has a r12 machine anymore. If one pops up around here cheap I'm buying it. I have had great success with Freeze 12. It's been in my DeLorean for 3 years now, and I used it in my old Accord for about 5 years. Never had a problem.

You already have converted to a less effective freon to satisfy the EPA. Freeze 12 and other R12 substitutes are not R12. They have similar physical properties, and are compatible with the oil used in R12 systems. They can be blended with or added to R12 in many cases, but they are not R12, nor to they cool quite as well.

In some cases these are blends of other refrigerants, mostly 134a with some others to keep compatibility. Sometimes they contain propane.

Aside from cooling capacity, the ability to blend, and not have to flush the old system, another motivation for using an R12 substitute is because the oem hoses were designed for R12, and by some accounts the smaller molecules in 134a can eventually weep out through an otherwise good hose. Newer hoses reportedly use a chemistry that seals effectively against 134a as well. The problem here is that when you put in a blended refrigerant, like freeze 12, the 134a component could weep out, and over time you will be running a gas in the system with different expansion properties.

I can't verify the validity of the claims of 134a weeping through.

I can say that the test to get an R12 license takes about 30 minutes, and its an open book online test. The last time I got R12 on ebay it was about $25-$35 a can.

[David T]

If you have the correct amount of refrigerant and it is not cycling, you may have to adjust the low pressure switch. If you remove the wiring plug you will see an adjustment screw between the to electrical contacts. before touching that make sure you are getting full airflow over both coils.
David Teitelbaum

[kings1527]

If you have the correct amount of refrigerant and it is not cycling, you may have to adjust the low pressure switch. If you remove the wiring plug you will see an adjustment screw between the to electrical contacts. before touching that make sure you are getting full airflow over both coils.
David Teitelbaum

Thanks, Dave. Should the compressor be cycling at idle or should it be constantly engaged? Like I mentioned before, I had heard 8 seconds on, and about 2-3 seconds off while at idle. Mine is currently constantly engaged at idle.

I'm definitely getting full airflow from the blower. I cleaned out every single thing when I installed my new evaporator a month ago. From the blower itself, to the inlet under the windshield to the evaporator drain tube at the bottom of the box and everything inbetween.

For adjusting the low pressure screw, how does that go? I'm hearing that I want to have it cut out at around 25psi (25-32 per the manual) on the low side but I need to make sure that it should be cycling at idle before I start making any adjustments with the LP switch.

Thanks!

[dmc6960]

For adjusting the low pressure screw, how does that go? I'm hearing that I want to have it cut out at around 25psi (25-32 per the manual) on the low side but I need to make sure that it should be cycling at idle before I start making any adjustments with the LP switch.

EVERYTHING is dynamic in an automotive air conditioning system. If you car is at idle and your blower motor is on high, then it is normal for it not to cycle. The reason? The low pressure never gets down to the low-pressure cutoff point in the low pressure switch. Reduce the blower fan speed and it likely will cycle as at that point the system isn't trying to sink as much heat, lowering the low pressure, causing the cycle.

If you adjust your switch to the lower end of the cutoff (25psi), then you'll get less cycling on a normal charge as it is more difficult to achieve during typical operation. Lower it too much and you WILL start to freeze your evaporator at highway speeds. You are unlikely to freeze it at idle unless you have a low blower speed, this is because the cooling fans cannot sink as much heat out of the condenser as highway speeds do.

Now, regarding your raising vent temps. It is atypical to feel a noticeable raise in temp during a normal low pressure cycle. It is also unlikely that a frozen evaporator is causing it. What IS typical though is higher vent temperatures at idle, than at highway speeds. Under what conditions are having concerns with your AC operation? Have you checked that both radiator fans are operating normally?

[kings1527]

EVERYTHING is dynamic in an automotive air conditioning system. If you car is at idle and your blower motor is on high, then it is normal for it not to cycle. The reason? The low pressure never gets down to the low-pressure cutoff point in the low pressure switch. Reduce the blower fan speed and it likely will cycle as at that point the system isn't trying to sink as much heat, lowering the low pressure, causing the cycle.

If you adjust your switch to the lower end of the cutoff (25psi), then you'll get less cycling on a normal charge as it is more difficult to achieve during typical operation. Lower it too much and you WILL start to freeze your evaporator at highway speeds. You are unlikely to freeze it at idle unless you have a low blower speed, this is because the cooling fans cannot sink as much heat out of the condenser as highway speeds do.

Now, regarding your raising vent temps. It is atypical to feel a noticeable raise in temp during a normal low pressure cycle. It is also unlikely that a frozen evaporator is causing it. What IS typical though is higher vent temperatures at idle, than at highway speeds. Under what conditions are having concerns with your AC operation? Have you checked that both radiator fans are operating normally?

Thanks Jim. I didn't know all this. So you're saying that it might be normal for my system to be doing what it's doing?

When I was testing everything, the ambient temp was around mid 60's in the shade and the radiator fans were functioning as they should. Everything comes on like it should regarding my fans; whether we're talking coolant temperature rising or switching on the AC. So I know I'm good there. But this entire scenario that I described with my rising/lowering vent temps was done while at idle. I remember having it on Max AC and I think my fan speed was on 4. I remember setting the fan speed to 1 or 2 to see if I saw a difference, and I remember the vent temps did drop a little once again (from around 45-48 down to 42 or so), again while at idle.

I'm going to do a full diagnosis on Thurs, with vent temps and gauge readings, compressor activity, and ambient temps and see where I'm at.

Just thinking about everything I did when I filled my system. Since everything was brand new, there was no oil in the system so I put about 5 oz of mineral oil straight into the low pressure line before I connected it to the compressor. Two oz for the evap, two for the condenser, and one for the accumulator. Then I digitally weighed my R12 going in so I know I have around 2.2-2.3 lbs in there. And there are definitely no leaks. I held 30mmHg vacuum overnight before I filled the system and I purged the yellow filler line on my manifold set before filling the system with R12. So I know I didn't contaminate the system. I can't see what else the problem might be. I'm going to go over and insulate the evaporator lines to help keep them cooler. I know my blower is working fine. I know the foam on the passenger's side vent needs to be redone but that wouldn't be a factor with this problem. My driver's side vent is perfect and the center vents are completely connected to the rubber attachments inside with good airflow through them.

I seem to remember feeling the compressor finally cycle at idle when I was doing those tests I described. This was after I had been driving around and running the system for a bit. It seems like the temp would finally drop when the compressor engaged but it only would engage for around 5 seconds or so and then cut out and hence the vent temp would go up for about 5 sec until the compressor engaged again. I'll have to double check all that but I'm 98% sure that's exactly what was going on. But all of this was at idle. Could this all be normal?

Thanks again.

[dmc6960]

Run a few tests with the AC gauges connected. First one, idle, NORM AC, fan speed 4. Next, idle, NORM AC, fan speed 1. Next, 2000rpm, NORM AC, fan speed 4. Finally, 2000rpm, NORM AC, fan speed 1.

The 2000rpm boost will give the cooling fans more power (alternator not at idle), and the compressor will be pumping a lot more refrigerant.

Note the high/low pressures when the compressor engages and cuts off, how long each cycle on and off is, and what the ambient and vent temperature is. If your measuring the temp with an IR thermometer, also get a couple readings on the high/low lines out the back of the compressor, in/out on the condenser, and the accumulator. That can also give a clue to the overall efficiency of the system.

Your readings do sound a little high for a normally functioning R12 system. What components are original, or replacements? Do you have stock cooling fans or replacements? If replacements please state what kind and who you got them from.

[kings1527]

Run a few tests with the AC gauges connected. First one, idle, NORM AC, fan speed 4. Next, idle, NORM AC, fan speed 1. Next, 2000rpm, NORM AC, fan speed 4. Finally, 2000rpm, NORM AC, fan speed 1.

The 2000rpm boost will give the cooling fans more power (alternator not at idle), and the compressor will be pumping a lot more refrigerant.

Note the high/low pressures when the compressor engages and cuts off, how long each cycle on and off is, and what the ambient and vent temperature is. If your measuring the temp with an IR thermometer, also get a couple readings on the high/low lines out the back of the compressor, in/out on the condenser, and the accumulator. That can also give a clue to the overall efficiency of the system.

Your readings do sound a little high for a normally functioning R12 system. What components are original, or replacements? Do you have stock cooling fans or replacements? If replacements please state what kind and who you got them from.

Ok perfect, thanks. Good to know on the NORM AC setting. I'll do all of that and report back.

I'm measuring with a regular digital thermometer and my radiator fans are DPNW fans from Toby. They're supposed to put out roughly twice the CFM at 1/2 the power compared to a stock setup. Other than that, everything else is standard. I do have a DMCH 140a alternator along with Hervey's split AC lines. But all of my other stuff is either original or purchased new from DMC CA, namely the evaporator and accumulator. Plus, I flushed the condenser and the high pressure AC line going from the condenser to the evaporator prior to installing everything. So in terms of a blockage, it'd be highly unlikely. Everything else was completely brand new, included the hoses.

Thanks again.