There a grinding noise under the hood of my 2002 Prizm emanating from the serpentine belt area. The sound happens when the air conditioner is OFF, when I turn the A/C on the grinding sound either goes away or diminishes significantly. The previous owner recently had the serpentine belt replaced and I was thinking it might be a belt alignment issue. I have not eliminated the alternator or the idler pulley but those seem to be long shots. I'm going to check into it this weekend but wondering if anyone had experienced something similar to this and what fixed it. Thanks, Phil.

Took a look at this over the weekend, ended up spraying the clutch end of the compressor with penetrating fluid and the sound diminished by about 90%. It now appears that the clutch is not completely disengaging - more testing this weekend.