R12 to R134 A/C compressor differences?

[franklinstower]

Is there a difference in the A/C lines and connections between the R12 and R134 compressors or are they the same? So, could I just put a r134 compressor in where I have an R12 without switching the lines?

 

I have a '92 leggy engine in my Vanagon and I want to switch the A/C compressor over to a newer R134 from the current R12 i have in their now. I still have not mated the A/C lines over to my Vanagon yet and want to know if the lines and fittings are the same on both compressors. What year did they switch to R134? Is it correct to assume the older r134 compressor ('95 or so) would fit with out mods?

 

Thanks,

[the3rsss]

The 134a runs at a higher pressure. Probably a good idea to replace the lines. Did the old compressor fail? You need to flush the lines. You can buy flush in any auto parts store. Blow the flush out with compressed air. Keep flushing till all the crap stops coming out. Drain as much of the old oil out of the compressor that you can. Replace the drier. Get a 134a retrofit kit with the new service fittings. Add ester oil in the correct amount. Hook it up. Vac. It down. Make sure it holds a good long vac. I charge with a dye can just in case. Finish charging and check for leaks. It will never work as good as r12. The metering valve lets in too much refrigerated. You can replace that if you want but I wouldn't bother. You will get cold air.

[the3rsss]

Just want to follow up.....if the r12 compressor is still good use that! Ester oil is comparable with r12 and 134. No need to switch compressors

[Rooster2]

Just want to follow up.....if the r12 compressor is still good use that! Ester oil is comparable with r12 and 134. No need to switch compressors

 

Yes, if the compressor is still good, then no need to replace it. Ester oil is compatible with the remnants of R-12 oil. It is the other compressor oil, PAG oil, that is not compatible with remnants of R-12 oil.

 

Years ago, I had a shop replace R-12 with R-134 in a 91 Subbie Leggie wagon. They opened the system, when replacing the engine. As far as I know, they did nothing more then just replace with R-134 and ester oil. R-134 cooled the car down great. No leaks resulted. System still worked good years later when I sold the car.

[franklinstower]

I am not sure on my compressor status. But from my readings, the better choice is to keep everything same and use a refrigerant such as red tek r12a. It is compatible with either oil, operates at lower head pressures, and has larger molecules than 134. Much better suited than retrofit 134 especially with such long runs in my vanagon.

Paul.

[the3rsss]

Flush is cheap! If the original compressor failed then you MUST flush your system. Pay paticular attention to the condenser. That seems to accumulate the most crude. If you don't flush after a catastrophic compressor failure your new compressot will soon fail, little bits of metal and crap floating around. I never heard of that other refrig. That you mentioned. 134a is cheap, available and works ok as a retrofit.

[Blue Whale]

I did a trouble-free conversion on my '93 several years ago. I added adapters to the external hose fittings, and I also replaced some O-ring seals (from the conversion kit; I don't know if it was really necessary to do that). I replaced the compressor, but not because of the conversion--the original had frozen up. The replacement was identical to the original, and also identical to the one in my '95, which was running with R134a from the factory. I didn't replace anything else, but just added the new refrigerant (the compressor came pre-filled with oil). After the conversion, there was no change in the efficiency of the system.

[jdemaris]

Is there a difference in the A/C lines and connections between the R12 and R134 compressors or are they the same?

 

The rubber used in AC systems with R12 is different then newer hose now used with 134. 134 has a smaller molecular structure and leak slowly through old R12 hoses. New hoses are called "barrier" hoses. They have a barrier liner in the ID to prevent leakage.

 

That being said, the difference is not huge. The leak with 134 in old hoses can be very slow.

[Rooster2]

The rubber used in AC systems with R12 is different then newer hose now used with 134. 134 has a smaller molecular structure and leak slowly through old R12 hoses. New hoses are called "barrier" hoses. They have a barrier liner in the ID to prevent leakage.

 

That being said, the difference is not huge. The leak with 134 in old hoses can be very slow.

 

I agree, the leak is very slow. It never presented any problem to me.