For awhile now (last 5k miles or so) my brother in laws 89 IROC 5.7 TPI AC compressor has been whining very slightly whenever it is on(AC or defrost).Never made a peep before that and blew ice cold even with 150,000 miles.Well today it got tremendously louder..it now sounds like a roots supercharger whenever it is on.If I tun it off..it makes no noise at all while the engine is running.Could this be the compressor..clutch or what?I know very little about automotive AC systems.I need to fix this ASAP.What should I look for?TIA

 

That would be the compressor itself.... the clutch typically makes noise when it's turned off, and shuts up when the compressor is in use.

Not much you can do except change it out. Recover the refrigerant; replace the compressor, accumulator/drier, and orifice tube, and every O-ring; maybe replace the hoses with modern barrier hose; put about 5 oz of oil in the compressor, put it back together, evacuate it, put the Freon back in.

 

Well, I just had the same problem last summer. The comp. was sized. You should be able to turn the comp. over by hand or using a 9/16th socket on the shaft bolt. My system was working fine so I was real curious to see what happened. I bought a rebuilt comp. from a buddy who works at a parts store so he let me have the old comp. (R-4) and no core charge. I did not have the tools to disassemble the comp. so I used a cut off wheel and cut off the steel band that goes around the comp. Man was I suprised. The comp. was perfect inside but no oil and one of the four pistons stuck in the bore and came disconnected from the crankshaft. If I would of just addes some oil. Oh well $315.54 later I had it working and converted over to 134A.

Auggie