Whining noise in serpentine system. A/C?

I have a whining noise (not a grind, not a scraping) coming from the serpentine system in my '95. It rises & falls in pitch with engine rpm until maybe 3,000 then it dies away and returns again once I shift. It sounds like the groaning from a starved or strained power steering pump

With no serpentine belt on, things are quiet and good.

It's difficult to pinpoint exactly where it's coming from, but I have verified the balancer is in good shape and not coming undone, I've replaced the tensnioner pulley bearing, the power steering pump (which looked like it was full of ATF if that matters) and I've pulled the old tired looking alternator and run it on a test bench at the parts store. It was quiet.

All I'm left with is the compressor (which I used a loaner tool to pull the clutch back just a tad, just to make sure that wasn't the issue).

I have one of those charging cans I got at the parts store with a gauge. When I connect to the low side, the gauge moves solidly to the green (but I can't get the AC clutch to engage yet, so I can't verify for sure if the system is still charged.

One thought was a leak has occurred and I've lost the PAG oil? Since the gauge moves, that tells me it's still sealed and unlikely.

I have a new compressor, dryer, o-rings etc to put in, but I don't just want to throw parts at it needlessly.


Your thoughts and insights are appreciated.

You might try spraying a small shot of WD40 on the grooves of the belt while the engine is running. If the noise immediately stops, it is coming from the belt. It seems the only cure is to replace the belt with a serrated groove belt like the hard to find "Gatorback" or Continental equivalent.

I did put on a brand new GM Delco belt, and it sounds identical to the used belt on it beforehand. I'm not so sure it's the belt making the noise, but I'll put the old one on and try the WD40.

Let me know.

No change when adding WD40 to the spinning belt.

As I spin the compressor pulley by hand it feels rough & crunchy instead of perfectly smooth like the new compressor I bought.

Likely culprit.

Glad you beat it down. Most of these compressors start leaking at the middle seam before the bearings go bad.

Changed the conpressor pulley bearing and all is well with the world again. It was a nice trick showing my kids how you put the bearing in the freezer for a couple hours....the pulley in the oven on HI broil with the pulley close to the electric heating elements....and wha-la!!  The bearing drops beautifully into place in the pulley.

I did buy another UAC compressor, dryer, orifice tube & seal kit in case the whole system doesn’t work....which will likely be the case after all this work.

Quote :

Changed the conpressor pulley bearing and all is well with the world again. It was a nice trick showing my kids how you put the bearing in the freezer for a couple hours....the pulley in the oven on HI broil with the pulley close to the electric heating elements....and wha-la!! The bearing drops beautifully into place in the pulley.

Did you swear the kids to secrecy, so as not to inform the wife that you are cooking auto parts in the kitchen, or cleaning them in the dishwasher again?

The pulley was fairly clean....but indeed there was a whisp of oil smoke that exited the oven when I opened the door.

It should all be good moving forward.