vent noise in 2001 C240
 

I have a 2001 C240 that has a clicking noise in the vent system when you start the car. The noise lasts about 15 seconds, then stops. It doesn't do it again until you restart the car, but the dash vents don't have any air flowing from them. I suspect that it's a vent flapper that's stuck but don't know how to be sure or how to fix it. Any thoughts??
Please respond to short451@windstream.net
Thanks!