2002 Pontiac Montana - Groaning from

[BIGPROFITT]

under dash? I have a 2002 Pontiac Montana. Every once in a while I will hear a groaning sound coming from inside the dash. I know it has something to do with the heating/ac because if I change the vent selection (where the air comes out) the sound will change or stop. When this happens I also hear something that sounds like a flapper closing. This all just started happening about a month ago. Does anyone have an idea?

 

[wde3477]

Could be a damper door not sealing off tight, or a binding that restricts the normal movement of the doors so they can't get to the right position. Hard to tell without being there.

Not sure if your model has vacuum or electric actuators. If vacuum, could have a vacuum leak causing the doors not to move fully.