Hi everyone I'm new on here. I'm having a loud rough idle or exhaust sounding noise happening only when my A/C is on. Only notice it when I'm slowing down and stopped in idle that's when the loud rattle like noise starts up. Stops when I turn A/C off. Cools great and blower/fan seems to work fine. Any idea's what this might be? Thanks for any help in advance!

Look to see if the belt is slaping or idler pully jumping.