Yes the little rubber flaps of the vent were visually vibrating but it turns out this isnt the source of the vibration ive been hearing (mostly in the morning when its cold). Once I put the trim back in place and the seats up the vent isnt an issue, but in the morning I can hear a vibration...
I've noticed that vibration of the cab (i.e.-bumpy roads, engine vibration,etc.) causes the rubber flaps of the pressure vent in the back of the cab to vibrate and make a rattling noise. Has anyone figured out the best way to mitigate this or noticed this sound coming from theirs?