Hi,

I replaced the serpentine belt 3 months ago to remove the squeaking sound.

Now with AC activated, there is a rattling sound around the tensioner area.
I can see the tensioner vibrate little harder, and the sound appears
if we shut off the AC, car runs fine.

I do not see or feel like it is an idler puller or possibly a water pump, but I could be wrong
any advice is appreciated

video link:

 

A cheap mechanic's stethoscope could be very handy in your case. Mine has always been able to isolate the noisy or worn-out component for me on multiple vehicles over the past decade or so.

 

Thank you, will pick one up from harbor freight today.
Crossing my fingers it is not the '$1000" tensioner.

 

Could be the A/C compressor clutch.

 

Start by spraying some water on the belt, if the rattle sound goes away it means it's not the tensioner

 

Did you figure out where was the noise coming from?

 

Q: Are you trying to diagnose your issue by following OP's problem? For that purpose, you are just looking at the odds/chance.

Or just curious?

Salim

 

Yes.
My '13 does exactly the same as in the video. The noise seems to stop when turning off ac. I haven't had time to get under the car but I'm looking at the possibilities.

 

Good advice there.

Await further feedback.