when the ac is not on the compressor just started making a humming or whining noise,but when i engage the ac,the noise stops.does it mean i need a new compressor?i sprayed some lubricant down there but the noise only goes away when the ac is turned on.never did this before,started today.suggestions anyone?since it cycles on and off it can't be the clutch,bearing maybe?if it is,is it a easy fix or a dealer fix?how much $$$ if anybody knows?