I have a 2006 GC with 135,000 miles, has a pronounced rawr,rawr,rawr,rawr at idle. The growl intensifies with the A/C on and disappears with increased rpm's. A/C works fine but the noise is annoying---sounds like a diesel hemi at idle Lately, the noise has switched to a high pitched whine when slowing down from hiway speed then reverts to the growl. Tried to isolate the noise, but it sounds the same at the alternator and the A/C compressor (difficult to pinpoint cuz its so loud) Searched the threads, but no similar situation. Any tips out there?

 

Alternator decoupler pulley

 

Yup, that's the one. I will search the threads for fixes. Thanks for narrowing it down for me!