When I start the engine cold, first thing in the morning, with the A/C 'on', I hear a squeal for about 10 seconds, then it goes away. It does not happen if I stop & start the car throughout the day, it must be idle for a few hours at least for the squeal to occur. Only happens during startup, not during driving. It started to happen after mechanic replaced belts.

I brought it back to him, he said there is a 'maroon' colored dust around the A/C compressor indicating that it is starting to go and should be replaced, that's what was causing the squealing. Does this make sense? Is there any way around this? Should I first try loosening the belt?

Why would this have not happened with my old belts, but when he replaced the belts, it started to happen?

 

The maroon colored dust is rust from the A/C compressor clutch. The fact that it's squealing now with new belts makes sense. The belts are gripping better and putting more of the torque onto the clutch disk. The disk is probably slipping and causing the squeal. It doesn't do it later in the day because the metal is heated and the clutch faces don't slip as much. First thing in the morning, they're cold and the gap between the two clutch faces is wider.

However, even a bad clutch doesn't mean the whole compressor needs to be replaced. He can replace just the clutch. Or, he can check the air gap when the engine is cold and adjust the gap with a shim. (On the other hand, the clutch has to be taken apart to do that and at that point you might as well replace the clutch.)

Bottom line--make sure it's the A/C clutch that's making the noise. Get an automotive stethoscope and use it first thing in the morning to isolate the sound.

How to diagnose squeaks and squeals

Rick