My ac compressor/clutch works fine when engaged. But rattles like a sob when turned off. I did a search but only found people with the OPPOSITE problem. Any ideas. Thanks Prorac1

 

It is probably the clutch bearing. It makes noise when the clutch is not engaged and the pully is freewheeling. When the clutch is engaged the bearing isn't turning so there isn't any noise. Mine did the same thing several years ago. I had the bearing replaced and the noise stopped.

As a side note I had a noticeable loss of power and gas mileage while I had the noise. I think the noise was interpreted as knock and my timeing was being retarded.

 

Thats what im thinking it was as well. What did it cost you to have done? Thanks Prorac1

 

It was 6 or 7 years ago and I had some other work done at the same time so I'm not sure what it cost. It was probably about $200 and I had it done at the dealer.