Problem Description and Possible Solution
The vacuum manifold for the climate control actuator may develop a leak, This can cause poor or no operation of the air delivery and temperature control flaps.
Average mileage: 123,387 (57,890–244,000)
26 people reported this problem
I had this problem last year. It was solved by reconnecting a vac line that was near the oil filter. The line was not immediately apparent but it drops down in the oil filter area to a connector which can inadvertently pulled loose during a filter change. When I found the line, I pulled slightly on it and it was apparent it was loose. I think I had to reconnect it from under the car. When reconnected, everything worked normally again.
Air does not flow from the center vents. MB dealer said it was the air-conditioning actuator, which needs to be replaced. They said it is a $600 to $800 repair at the dealership and could be fixed for much less at an independent shop (recommended that due to the car's age and value, especially since its not a critical safety system).