I have a 1985 300SD and it seems like the AC compressor is about to go. I say this because it's making an unusual amount of noise, leading me to believe that the bearing will soon go. I also noticed around the pressure lines that lead into the unit, what appears to be compressor oil(clear, not black like diesel oil) It is not gone yet as it is still relatively cool. My question is, do I just replace the compressor with a new one? Or do I have to go Compressor, expansionvalve etc... Fastlane does not carry the compressor. If someone can provide the model # to purchase from GM, I would appreciate it. Thanks

I would suggest replacing the compressor and dryer. Have them flush it, pull a good vacuum, add the necessary amount of oil and then top it off with r12 refrigerant. Some other members may come along with some more suggestions but this should get you started. You can get a compressor at AutoZone, Advance or places like that (just give them you car make/model). Only purchase a new compressor - don't try the rebuilt route.
Try to stick with r12 or go back to it if you are now running r134. You will need to make sure you have eliminated all the leaks in the system too.

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Jim

It's making noise because it's on the way out, low on freon or the belt needs to be adjusted. A loose belt will result in not enough pressure build-up for proper operation and could mislead you. They kind of sound like they have a bunch of large nuts and bolts rattleing around inside. Especially at idle.

So I would snug up the belt first. If the problem persists, have the system checked for leaks when adding freon. Then go for the compressor. Sounds like you may have a hose leak. If so now is the time to replace them all. If there is any good news here it is that your compressor with a new clutch is probably the least expensive of all to purchase. If it's bad - buy new as already mentioned.

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Art Bourget

1983 300SD
1st In Class - Starfest Concours 2004
1st In Class - StarTrack Concours 2003
1983 300TDT
1985 300D

MBCA - Niagara Section

Make sure that the compressor is firmly mounted. Check the tightness of all mount bolts. If they get a little loose, it will sound terrible.

I have run noisy compressors for several years in the Texas heat before they actually fail.

Good luck,

I am not very patient when it comes to A/C

Bought new r-4 compressor and drier for about $270.00 wholesale from local distributor. AHd my mechanic mount and install 134 and everything is wonderful.

Thanks for the advice.