Most belt noise is caused when one of two conditions. Either the belt is loose or it is worn (indicated by smooth shiny surface on the pulley side) and should be replaced.
low on freon compressor kicking in and out
Bearing in: Alternator? Water pump? A/C Compressor? Belt tensioner?
If this is a general noise, it could be the transaxle. When you are accelerating, the engine is pushing the gears, and when you let go of the pedal, the vehicle starts to shift back down. If this is an engine noise, it could be predetonation or a valve problem.
the universe is noisy. eliminate all other noise sources and you still have the big bang.
APC
Bad bearing in compressor? Bad bearing in compressor?
It makes noise and cools everything.
Yes
Have a noise cancelling headset will help a great deal to eliminate background noise.
Somthing to do with the AC.
Remove the compressor and pour it in. If its making noise its probably to late and you will need to replace it.
If the clutch disengages properly then the compressor should not be running. Most likely the clutch itself is bad instead of the compressor.