My 07 Escalade started making a noise from under the hood and I found the AC belt tensioner vibrating. I changed out the tensioner and the belt still vibrated. I put a new belt on and it fixed all the squealing and vibrating for now. I looked at it after driving some and the tensioner has a tiny amount of vibration and it looks like the belt is starting to wear some.

Anyone ever had this issue? I'm starting to wonder if the AC clutch is going out. It doesn't make any sounds and works fine, but there is a reason these belts are going the way they are.