R12 system compressor replacement

[mikemo]

Hello all. I'm hoping I can get some guidance on a repair.
I have a 1988 Toyota MR2 Supercharged that I've been slowly restoring over the last 7 years. When I got the car the AC system was completely empty, and one of the schrader valves had a R134 adapter on it. Very strange. Since I didn't know the state of anything I wanted to get things at a good starting point.

I replaced the drier and expansion valve. Flushed the lines, condenser and evaporator with Duraflush. Removed the compressor and flushed with mineral oil several times to remove whatever oil was there to the best of my ability. I also replaced all the orings in the system and added the correct mineral oil charge with some UV dye. I wanted to replace the compressor but the correct one was not available from anywhere I looked.

I had the system pumped down then recharged with R12. Temperatures and pressures were good, so I called it "fixed".

Now, 7 years later, I can see some UV oil on the snout of the compressor. I looked again and found a rebuilt compressor is available. However, it seems that all the rebuilt compressors assume that you will be using R134. This compressor says it has PAG oil already in it. Am I safe to flush the new compressor with mineral oil, then install, or is there something else I need to do to guarantee compatibility of the new compressor with R12.

And, of course, the R12 in the current system will be recovered before the repair.

Thanks in advance for any advice.
Mike M.

[Tom Greenleaf]

Yes - dump out any "PAG" oils for mineral of the same amount. If compressor burned out you need to know so catch that oil for inspection for debris if so this is a start all over again job possibly? Can't know till you check and brace for more than the compressor. Do replace receiver/drier just anyway. Keep count of oil lost for an idea what to put back,

[Cusser]

I looked again and found a rebuilt compressor is available.

See if brand-new compressors for this are available, might be very similar in price to a rebuilt one these days..

However, it seems that all the compressors assume that you will be using R134. This compressor says it has PAG oil already in it. Am I safe to flush the new compressor with mineral oil, then install, or is there something else I need to do to guarantee compatibility of the new compressor with R12.

Thanks in advance for any advice.
Mike M.

Yes, I've had to do this as well. I drained the new compressor (one should do this regardless - never trust that the right amount has been added). When i was working I could test for type of oil already in the new or rebuilt compressors. About 15 years ago I bought an AC Pro rebuilt unit for my '88 Mazda truck that was R-12, it had PAG oil in it. I drained that, added 6 oz mineral-type R-12 oil, turned it like 10 revolutions, drained that. Then did that again and drained. Then I added correct amount. That rebuilt (from ACkits.com) lasted me 11 years, and was replaced with brand new a few years ago.

Funny, a month after that rebuilt was done, my co-worker got an AC Pro compressor for his 1990 Mazda Protege from ACkits.com and that had the correct R-12 oil in it.

[hectorsalls]

I agree with you Cusser.