Automotive Air Conditioning Information Forum

Hello everyone, I had a question concerning PAG oil compatibility with an older R12 system. The new compressor I purchased came with PAG 100 installed. I have heard that this might have some adverse effects, seeing how it is impossible to drain and flush out the remaining refrigerant and oil with the limited tools I have on hand (air compressor, no flush gun). I plan on converting it to R134a, as I also purchased new hoses, receiver/dryer, and the expansion valve.

The new compressor and components are made by GPD for a 1990 240 Volvo. The previous compressor was a diesel-kiki that had seized up.

For longevity, is it safe to use PAG 100 in this case, or do I have to drain and refill with Ester oil?

Thanks for the help guys!

I would go with the Ester the PAG and old mineral oil will not play well together. I think you already knew this you just wanted confirmation LOL CONFIRMED

If mine: I would drain the PAG oil from the compressor, then flush the compressor a couple of times with R-12 mineral oil, then fill with correct amount of mineral oil and use R-12 refrigerant.

In fact: that's EXACTLY what I did 2 years ago on my 1988 Mazda truck. It will cost you more overall to go R134a; the difference is inconsequential unless you keep having leaks.

Thank you both for what I suspected I needed to do. Better to do it nice then to have to do it twice!