Hi all, new here. Just purchased my '03 AT Coupe at 34k.

I can hear a faint rattle with the window open but only if 1) the heat is on and 2) the engine is at idling RPMs

Is there a cause for concern? Anything to look further into?

TIA

Is your window down all the way? if it isn't, I would guess that if you are running a/c with heat (which you shouldn't have to) it could bump your rpms up a tad to give your door a vibration to rattle your window around.

I just meant hitting Auto Econ set to 68 while it's 33 outside. So i popped the hood and it is definitely coming from there, but hard to locate. I don't hear the noise at all when the air is off, so I don't think it is belts, but something related to the air system.

Sounds like a rattle my coupe has at idle. With windows up or down, ac on or off, at idle only. I tried to locate the source and while stepping onto the right rear floorboard to listen around, I noticed it stopped with my weight applied. So I guess it may be an exhaust rattle and need to get it checked out.
'03 Coupe 5AT