Please be kind, this is my 1st post.

My 2007 Suburban sounds like there is a hamster running in a squeaky wheel. It's driving me crazy and I can't seem to pinpoint the culprit.
I have replaced the water pump, serpentine and a/c belts, the tensioner pulley and the a/c pulley. Any insight would be appreciated!

 

When does it do it? At idle? While driving? over what speed? with ac or def on? anymore info would help

 

At 1st it seemed more pronounced when I'd accelerate. The a/c, heater, defrost don't seem to effect the noise (volume or frequency). I don't notice it when I'm on the highway (usually), but it squeals when its idling too. I haven't replaced the idler pulley yet-wanted to see if you all had any ideas.
Things to note: The belts and water pump were replaced by a mechanic. The other work was DIY. I've tried the soap trick, but didn't really help.
I do notice that if I run a toothbrush along the grooved-side of the belt, to the right (driver's side) of the idler pulley the noise stops.

 

Use a spray bottle with water on the belt does it go away. There may be 2 different belts available based on alt amperage, your belt could be the wrong one.

 

I'll try it in the morning (underside over top of the belt?) and get back with you. I thank you for your help! If it is in fact the wrong belt, will the shop that installed it be responsible for correcting the oversight? Just wondering.