My 1993 300E 3.2 does exactly the same thing. There is an loud annoying flap from the dash when the car is started. Leaving the control in normal mode with the fan on low when shutting down the car alleviates the problem when you later start the car. My transmission also shifts somewhat abruptly between 3-4 when cold. Is this an indication of a potential problem or something that is a simple adjustment? Just purchased the car 1 month ago. 92,000 miles.