Silly A/C mistake.

Hi All,

I'm removing the engine from my 1999 Pontiac Montana van to replace it with another. This van has working A/C which is mandatory for my wife. While separating the compressor from the engine (leaving the lines intact to keep the A/C charge) I accidentally removed the compressor oil drain plug and lost a bit of oil. What is the best way to check and add oil back into the compressor before I put the engine back in and the compressor is buried again. I am assuming that this oil is separate from the freon oil? There was no pressure in the compressor when I undid the plug.

Thanks in advance for your advice.

I never heard of an AC compresor having a seperate oil sump. Normally, if oils is lost, you replace the amount lost. No pressure means you have already lost your Freon. That's my guess.

Yeah, modern automotive AC systems have the compressor oil mixed in with the refrigerant. If there was no pressure loss my guess is that there was no refrigerant in there before.

I was hoping that the system was charged but I did not check it. If it is empty that is going to be expensive to fix. I was hoping that the oil was in a separate chamber of the compressor and could be filled without disturbing the freon charge. Rats.

I just pushed on the AC line valve. There is still some pressure in the system. Maybe I can get by with just adding some freon and not get a new drier and vacuum it down etc.

The old York two cylinder A/C compressor is the only one I am familiar with that has a seperate sump. Doubt there is one on a 99 anything.

I guess that I have messed up the freon charge. I can't buy the R134A in cans up here in Canada to recharge it myself. I'll have to take it to a shop when I get the new engine in and running. Thanks for all of your replies.