Any time you evacuate the A/C system, you have to replace the receiver/dryer. Unless you live in a vacuum. Humidity is bad for them. My truck has the same issue with the AC clutch squealing whenever you start the truck or turn on the AC or sometimes the heater/vent. Usually goes away when you either rev the engine way high or put it in gear.

 

Eff10, I knew what you meant. Nothing I talked about deals with the main shaft bearings in the compressor, just the bearing that the pulley rides on. Once you get into it, you'll see.