PeachParts Mercedes-Benz Forum - View Single Post - VERY LOUD slapping air vent upon cold start.

ksing44 · #7 02-08-2006, 06:11 AM

Quote:

Originally Posted by flanso

The failsafe mode for the system is with the defroster on so when the engine is turned off, the vent door opens to defroster mode. When you restart, vacuum pulls that door closed with the resulting clunk. I suppose the vent door could be replaced or new foam installed but it took me about 6 hours just to get face to face with that door.

I wasn’t sure if I had a leak and less vacuum or too much vacuum. Based on your description, if vacuum pulls it shut upon start-up, then it seems that I have more vacuum after the transmission repair. I really think there is some adjustment with the vacuum that has my car shifting a bit oddly when cold and that also affects the vent closing. I have just a very slight flair with shifts between 3 and 4th gear. The dealer adjusted something and it helped the flair a bit, but it still does it a little too. The slapping vent started with the throttle actuator repair, so I am convinced that they are related. It is possible that it is just a coincidence, but I think there is a connection.