C 230 (203.040) L4-1.8L SC (271.948) (2005)
Air Duct: Description and Operation
GF83.10-P-2105-01P Rear Vent, Function
Lamella-type flaps attached opened to the rear vents are by the head pressure of the air flowing through the vehicle allowing it to escape.
If there is a negative pressure in the vehicle, as when driving with the windows open or with the sliding roof open, the flaps will be closed automatically
through the force of gravity. This way they help to avoid any exhaust, dust or moisture from being drawn into the vehicle.