Originally Posted by trialskid
try switching from vent to recirc and see if it makes the noise. it definitely sounds like a jammed mode door
I can't seem to find a situation where the noise does not occur.
vent on (no recirc) = noise
recirc on = noise
HVAC off completely = noise
Auto HVAC on or off (manual) = noise
A/C on or off = noise
The fact that even when the HVAC is off completely the noise occurs is somewhat surprising.