Dear Dave:
Thanks for such a knowlegable reply. Allow me to answer some questions and then ask you (and the others reading this) a few more of my own.
The system is converted to R134a. I will check the charge level soon, but the vehicle is regularly serviced and I know (think) it was checked last summer (and the compressor was groaning back then as well).
So assuming my system is charged, and assuming adding two ounces of pag type oil does not quiet the compressor down, then I assume my compressor has issues, correct?
I guess the first decision is whether I convert to a Sanden type compressor, per the link that Commando 1 sent or just rebuild my current Tecumseh.
I am NOT a mechanic, and I fear the complexity of a Sanden conversion. But I will do that if everyone feels that's the best solution. What do you think of simply going to the Original Air Group and having my current compressor rebuilt? And while I'm at it, checking all the other components--evaporator and condensor--to make sure they are up to snuff?
I seek the simplest solution, even if that costs a bit more.
Finally, since it's winter here, I don't use the AC. But the compressor runs even when I just use heat, and so I assume that given the groaning, this is not somerthing that should wait?
Thanks,
Peter
The compressor runs when you use defrost so the evaporator can dry the air before it goes to the windshield. The advice to unplug it until it can be looked at is very good advice. The fact that it has been left to do this for so long is troubling, but it isn't a conclusive indicator of a damaged compressor... just an unhappy one.
You may get lucky and a proper oil charge is all she needs to go for sometime longer. Now that she is on R134a refrigerant, there should be at least an annual checkup. Most newer techs are completely unfamiliar with these, and I must admit... my experience with them is limited as well.
You did buy an FSM a while back IIRC. There will be a set of instructions there for checking the oil in the compressor. This is shop work, because it involves discharging the system. The recommendation to add a couple oz. of oil to see if it clears the noise is more diagnostic than repair.
The 2 issues working against you without draining and fully refilling the compressor are:
1- contaminated oil, caused by an improper conversion to R134a by whomever did the job
2- low refrigerant oil caused by leakage and/or improper filling procedures.
These compressors have an oil sump and take a lot more oil than more modern radial designs. It wouldn't be at all uncommon for a tech to not find or not follow the directions to check/fill the oil in one because it would be completely different from their experience with any newer design.
More simply... just disconnect the compressor clutch electrical plug, and you can run without the compressor without (much) risk of damage. A bad bearing on the pulley would be the only concern left, you'd know, because it would make terrible noise and eat the belts... immediately.
Review your FSM and offer it to the shop who is doing the work for you. It helps to understand the repairs, but doesn't help to get too overbearing with a tech... if they think you're crazy, you may need a different tech. I would expect them to be open minded when you express the concern and show them the procedure in the book.