Red Tek

[David T]

Using Nitrogen is an extra, time consuming step and added expense so many shops just skip it. It is especially necessary to do on a "dead" system because, as you say, you can't test it if it isn't charged. I stand by my words of no one should still be using 30 year old A/C hoses. Check with your local shops and see what they say about that. I like using Nitrogen because it allows you to pressurize the low side to a higher pressure so you can find the smaller leaks. Under normal use the low side never gets above 70-80 psi and that is only when the system isn't running. I also pull a harder vacuum than most shops who vacuum til the gauge stops moving and then shoot the refrigerant in. I get to at least 400 microns and I hold it for at least an hour so I KNOW there is no moisture left in the system. All of this takes time, time most shops don't want to spend. Because if they did they would have to charge the customer a lot more.

[Bitsyncmaster]

I get to at least 400 microns and I hold it for at least an hour so I KNOW there is no moisture left in the system. All of this takes time, time most shops don't want to spend. Because if they did they would have to charge the customer a lot more.

Can you post a photo of your vacuum pump and micron gauge? I'd like to know what works for you to get that good vacuum. Also do you own a nitrogen tank or rent it?

[DMC1890]

Red Tek sounds like the way to go for me. I'll report back in a few days after I've done it. I read an interesting perspective on 134 on Hagerty's web site, saying that many European/Japanese cars from the 70s/80s had A/C that was already marginal on R12 (they don't have Houston's climate to deal with!), and that 134 just makes matters worse.

I'll take my chances on the old hoses, but...

37 year old tires? No, it's not worth the risk. 37 year old AC hoses in good condition? I say, knock yourself out!

My tires are old enough to vote - and new ones are on order.

[DMC-81]

Using Nitrogen is an extra, time consuming step and added expense so many shops just skip it. It is especially necessary to do on a "dead" system because, as you say, you can't test it if it isn't charged. I stand by my words of no one should still be using 30 year old A/C hoses. Check with your local shops and see what they say about that. I like using Nitrogen because it allows you to pressurize the low side to a higher pressure so you can find the smaller leaks. Under normal use the low side never gets above 70-80 psi and that is only when the system isn't running. I also pull a harder vacuum than most shops who vacuum til the gauge stops moving and then shoot the refrigerant in. I get to at least 400 microns and I hold it for at least an hour so I KNOW there is no moisture left in the system. All of this takes time, time most shops don't want to spend. Because if they did they would have to charge the customer a lot more.

David, none of the upscale shops I visited even had equipment for a nitrogen charge. It's not like it was an extra charge service. Perhaps it is common where you are, but not here. If you like it, that's great. IMO I think that charging the low pressure hose to twice operating pressure is inviting leaks where none existed before.

Can you clarify "400 microns"? Because 400 microns of mercury = 0.02 inches of mercury (inHg) and even 400,000 microns of mercury = 15.75 inches of mercury. You would need 762,000 microns of mercury to equate to 30 inches of mercury which is max vacuum on my newish gauge.
I have asked shops about the hoses, keeping in mind my goals for my car... originality. They basically said if they are not leaking and in good condition, and you are staying with R12, then keep the original hoses if you want.

[David T]

The "equipment" to pressurize with Nitrogen consists of a tank and a pressure regulator. You have to buy the 1st tank and from then on you just exchange when empty for a full one. You also have to buy the regulator. The tank costs about $22 to refill and lasts for about a dozen cars, less when you use it on larger systems like a house central A/C system. My vacuum pump is a RobinAir model 15101-A and my vacuum gauge is a Supco Model VG-61. You cannot measure a hard vacuum with a compound gauge, not accurately anyway. I can actually see when I have the moisture out by the way the vacuum decreases if I shut the valves to the vacuum pump and watch the system vacuum. You can also use Helium for even smaller leak detection but Helium is more expensive but then you can also use it to blow up balloons. If you are interested in this kind of stuff you should go to a local supply house that services the A/C tradesmen and talk to the counter guys and they will hook you up with what you need.

[hippieman9]

The only thing left to say is, does it work as good as R-12?
.

I have been running Red Tek in North Carolina this summer with 80-90 degree weather and it is ICE cold in the car. No complaints what so ever. I spoke to Red Tek as well and they don't list the product as being compatible with R12 because R12 is illegal to sell. So they only list it as a replacement for R134a. But It does work and work well. No issues here!

[Spittybug]

I have been running Red Tek in North Carolina this summer with 80-90 degree weather and it is ICE cold in the car. No complaints what so ever. I spoke to Red Tek as well and they don't list the product as being compatible with R12 because R12 is illegal to sell. So they only list it as a replacement for R134a. But It does work and work well. No issues here!

Did you evacuate the R12 and pull a vacuum, or did you just add the Red Tek in?

[hippieman9]

Did you evacuate the R12 and pull a vacuum, or did you just add the Red Tek in?

My car was converted to Red Tek by DMC CA a couple of years ago. When I purchased it this past March and the A/C was not blowing cold, I just recharged it with a can of Red TEk and its perfect.

[DMC1890]

Did you evacuate the R12 and pull a vacuum, or did you just add the Red Tek in?

I did this yesterday. I still had a small amount of pressure (R12) in the system (~1 Bar), even after at least 8 years of non-use. I thought it would be best to evacuate and pull a vacuum so that I would know that the system would then contain only Red Tek.

The kit I bought included a hose/gauge, can of leak stop, and 2 cans of refrigerant. The hose has a R134 fitting, and the kit did not include an R12 adapter, which Red Tek sells separately. I used my old gauge set which has native R12 fittings.

The leak stop, plus the 2 cans of refrigerant matches almost exactly the equivalent of the 2.5 lbs of R12 that is specified for the D.

I ended up with the following results:
Ambient temp 90 deg F
Engine idling at 850 RPM
Blower on speed 4, recirc 'off'
Low side pressure - 40 psig, High side - 160 psig
Outlet temp - 64 deg F

Static pressure - 67 psig (low and high)

I may be slightly low on the charge, based on the measured pressures, but I didn't want to tap another can just yet. I assume that at driving speeds, and at lower blower speeds, and on recirc, that I will have lower outlet temps. I still don't have current TX state inspection and registration, so I've kept a low profile on the streets.

[Morpheus]

The proper charge amount of RedTek for the DeLorean is 11oz. You have way too much in the system.

The Leak Stop can contains 2 oz of RedTek and 4 oz leak stop. One can of RedTek is 6oz. If you put in both cans of Red Tek and the Leak Stop, you have 14 oz of RedTek in your system.