Loud HVAC pop/noise

[Cactuar]

Hi all. When I first start the car and switch the air from feet-only to mid/feet/defrost, a loud pop can be heard.

By removing the center grille on the dash and sticking a light in there I could see that the popping noise comes from the bottom flaps, maybe from assembly # 64111374325 (#3 here)?

In the video below you can hear it just as the flap opens (the flap is barely visible in the video, it's at the very bottom of the opening).

Is there a way to make the flaps quieter, ideally without taking the dash apart? Thanks

[shogun]

Check the stepper motor on the side which moves that flap, maybe it is lose of like on my one the holding clips were too soft and slipped out. I fixed the stepper motor on the left side with a zip tie. Some pics when we fixed it http://www.bimmerboard.com/forums/posts/1091582/ The pics we made on a spare IHKA unit.
Or:
Originally there is foam on the flap ends and that has disintegrated and maybe the old glue/foam sticks a bit.

[Cactuar]

Great thanks for the link Shogun, as always you're very helpful.

I will try to find out if the flap is sticking somehow.