Automotive Air Conditioning Information Forum

I'm redoing my AC system (1980 300D) and was going to keep using the original compressor (still works), but thought it worthwhile to go new (reman) since I'm replacing everything else. System still R12 and thats what I'm filling with.
However, the new R4 compressor came pre-filled with 3oz of PAG-150. I tried to dump it out, but not even 1/4 oz came out. I know this will NOT mix with my mineral oil I have ready to install in the system.

New compressor has a circlip-closed drain plug. Do I open this up and try to get it all out? Is this going to do the trick? Everything I see says to NOT flush the compressor. I don't want to mix the two and have gel floating around in my system. All insight welcome.

You're planning to keep it R-12, so I too would replace the compressor since the R4 is not exactly known for it's trouble-free performance. You definitely don't want to get the system nicely evacuated and re-charged with precious R-12, and then have the rebuilt compressor go out shortly thereafter, along with all the R-12.

If you're going to keep the R4 for the sake of ease-of-mounting, aesthetics, and so on, I would replace the original compressor with a brand-new R4 (not reman or rebuilt) that already comes from the manufacturer either empty of oil or with a partial fill of the correct mineral oil. Also replace the R/D at the same time.

Tim at ACKits.com, this Forum's sponsor, might be able to help you locate the suitable parts.

John is right on, as usual, with all his comments….and I want to specifically underscore to never buy a reman compressor….you’ll end up doing the job all over again in a short amount of time.

In 2014 I bought a brand-new compressor from this board's sponsor, for my 1988 truck; compressor came with PAG oil - tested a drop of the oil at work. Since I was staying R-12, I dumped out all the PAG oil out the low'/high ports, added a few oz. R-12-type mineral oil, turned the compressor drive plate like a dozen times, then dumped that oil.

Then I repeated that step.

So only after at least two R-12-type mineral oil flushes, I added the correct amount of R-12-type mineral oil and finished the job. The truck and the compressor are still working fine.

Co-worker also bought a new compressor from board sponsor a few months later for his 1990 vehicle (same make as mine); he was also staying R-12. His compressor came filled with R-12-type mineral oil. Go figure.

Thanks all. Much appreciated. I ended up calling the manufacturer and they were quite helpful, offering similar advice. I dumped the PAG and rinsed with mineral oil (3 times) then mounted up and all seems good so far.