I am having a problem with the compressor not spinning on my 04. The air blows cold and I have no problems when the air conditioning is on. When the air is off however the compressor will spin a little then stop, over and over again. I heard a horrible noise this morning when I turned the engine on which has the belt just spinning over a stopped wheel. First thing I did was turn the air on and it did'nt skip anymore. I think this is probably the clutch but i'm not the best mechanic that's for sure. Any ideas of what I should do next?

 

the a/c compressor doesnt always spin, it has a clutch and comes on when needed.
however the pulley does free wheel when the a/c is off and the bearings can go bad and make alot of noise
but the front of the compressor not spinning all the time is normal