2003 c230 k vent ckicking noises when engine starts

any ideas guys. when i start the engine the vents click open and close and they make a clicking sound. the ac works fine and so does the heater.
anyone else have this issues

 

have any pictures

 

Sounds like a broken stepper motor or linkage. you have to remove the dash to figure out which one is faulty. not an easy repair.

 

I JUST HAD THE SAME PROBLEM... FAN MOTOR POSITION FLOW ARM. AT IGNITION OR START UP. THE ARM SETS ITSELF... THATS WHAT THE CLICKING/KNOCKING SOUND COMES FROM. WARRANTY COVERS. GET IT FIXED. SAME DAY REPAIR