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Ken Dahl · 06-22-2019, 08:14 PM

1992 Fleetwood Pace Arrow on Chevy P30 frame

I want to/need to convert my AC system from R12 to R134a.

I see kits online but they all include an air compressor. Mine was running fine do I really need to replace it? Besides a bunch of O-rings what else do I need to replace?

Thanks fellow travelers

Ken

aether_one · 06-22-2019, 08:22 PM

Air compressor?

MinntoMich · 06-22-2019, 09:33 PM

If your going to convert to R134, I think your going to want to vaccum all the old R12 out. Harbor Freight carries vaccum pumps at a reasonable cost.

You may have to add oil to your system. If your pockets are deep, you can buy "recycled" freon or I think there is a substitute marketed under the brand name Envirosafe and is in the neighborhood of 6 to 10 dollars a can. No need for all the worry and money for a complete system change. I have not used this product but have heard about it 1st hand.

Me... I would add freon if I could or use Envirosafe and go. Your in California so good luck with that.

Hard to find a good replacement for R12 and is seems there nothing really ever environmentally safe. Sometimes the substitutes end up being just as bad.

450Donn · 06-22-2019, 09:38 PM

The conversion is not a simple DIY project. It is against the law to simply open the system and release the R12. Then the entire system needs to be taken apart. All seals, orings, dryer need to be replaced. Then the system needs to be evacuated, leak tested before you can add the R134a

Nick-B · 06-22-2019, 09:48 PM

The R134 refrigerant runs at significantly higher pressures than R12. While people have converted their systems to R134 and they will initially work OK, some experience leakage and outright system failure.
The Envirosafe refrigerant mentioned above would be a safer substitute for R12 as it runs at similar pressures. I have used it myself in an old Jeep Cherokee and was pleased with it's cooling performance.

MinntoMich · 06-22-2019, 10:17 PM

Quote:

Originally Posted by 450Donn

The conversion is not a simple DIY project. It is against the law to simply open the system and release the R12. Then the entire system needs to be taken apart. All seals, orings, dryer need to be replaced. Then the system needs to be evacuated, leak tested before you can add the R134a

Nets full of advice for retrofitting to R134 (soon to be replaced by R1234YF?) from R12. Kits are plainly available to the public.

I think the law in question applies to mechanics who are required to reclaim and recycle the old refrigerant. We the consumer are prohibited by the rarity (manufacture of R12 banned or extreme cost of obtaining R12 from horded stocks).

I think your going to want to make sure your system is intact and no outside atmosphere (moisture or dust) is present. I have not done this myself so maybe better minds can speak to it. I'm not an attorney either but nonetheless I say go for it.

Dom · 06-22-2019, 10:46 PM

Quote:

Originally Posted by Nick-B

The R134 refrigerant runs at significantly higher pressures than R12. While people have converted their systems to R134 and they will initially work OK, some experience leakage and outright system failure.
The Envirosafe refrigerant mentioned above would be a safer substitute for R12 as it runs at similar pressures. I have used it myself in an old Jeep Cherokee and was pleased with it's cooling performance.

Actually r134a has a slightly lower pressure that r12. One problem in using r134a is that the cut out pressure switch is set for a higher pressure for r12, causing compressor to shut down too early. That being said, you can always replace switch with one for 134a. Also does you unit actually cool now with the r12?

twinboat · 06-22-2019, 11:38 PM

I converted my 1988 Ford F150 to R134a about 4 years ago.

I used an old refrigerator compressor as a vacuum pump and sucked down the system for 2 hours. I then added the oil and refrigerant according to the instructions.

I only drive the truck while picking up supplies and moving my boats, so use is very limited. I have since add 1 can of R134a last spring but it's still working.

D Gardiner · 06-23-2019, 12:16 AM

Considering your vehicle is a 1992 GM product, and I am assuming your current R12 system is empty of old freon, this conversion is somewhat straight forward.

Some caveats first, for success:

*If there is any R12 remaining, a local automotive A/C shop can evacuate the system
*Being the system most likely has the original O-rings, you will want to replace them all.
*If your compressor is good, you will need to drain the old R12 oil out. Which means removing the compressor from the RV.
*You will also need to flush the old lines, hoses, condenser and evaporator clean with freon cleaning solvent. https://www.amazon.com/System-Flush-.../dp/B009PVEXE4
*Replace the expansion valve.
*Replace the receiver dryer.

Once you have performed the above, the system is clean. Next,...

*Fill the compressor with the factory amount of 134a compatible freon oil, and install to the RV.
*Evacuate the air from the system, and verify that it holds a vacuum.

If so, you can fill the system with the factory specified amount of freon. Further notes. 134a uses a smaller molecule so you may need to refill the system more frequently. The other option is replacing the old hoses with 134a barrier hoses. You Xander also order many of these parts at www.rockauto.com

Removing the old oil and flushing is paramount as the old oil is not compatible with 134a.

Ken Dahl · 06-23-2019, 12:55 AM

One thing that comes to mind is that is way more complicated than I thought. I’ll see what his shop is going to charge me and decide from there

Dom · 06-23-2019, 07:11 AM

Back in the early 90's when r134a was just coming out, they said you would need to change the oil from mineral oil to polyolester oil because the new refrigerants did not mix well with mineral oil. That was in theory. In fact, in a close couple system, meaning that not a lot of distance between compressor and evaporator, it has been proven, hundreds of thousands of times, that the oil does return to the compressor. Back then, I took an old bar fridge that purposely used mineral oil, and charged with r134a. Gave the fridge to a friend and told him, if it works, it works. I asked him about 5 years ago, and it was still working at that time. The fact is, although r134a does not mix well with mineral oil, when the oil gets in the evaporator, it has no where else to go bit back to the evaporator. if you are working on a cooler, ect, where the evaporator is, lets say 10 feet below the compressor, as in a store with cooler on floor and compressor on roof, then mineral oil will not work.

Dom · 06-23-2019, 07:18 AM

One thing else to consider, especially in an older vehicle, not worth putting a lot of money in. If its still cooling a little, adding r134a to r12, it only becomes an isotope, meaning a new type of refrigerant, which in fact will work. One refrigerant we used to work with on walk in freezers, was r502, which was in fact an isotope of r12 and r22

Soppy · 06-23-2019, 07:46 AM

When I changed mine from R12 to R134a , I replaced the compressor (old one was shot), air dryer , lines, misc items and all the "O" rings. The system was flushed several times with a cleaner with the compressor disconnected. The correct amount of oil was added , then the system was evacuated and charged. You can easily do all the work yourself except for the evacuation and charging of the system.

Waiter21 · 06-23-2019, 09:47 AM

If the system is working ok, then I would not do the switch.. You can purchase original R12 or R12 compatibles on e-bay at reasonable costs, compared to 20 years ago.. (I think I have a couple cans of R12 in the barn...)

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