MB C240 Front Windshield Defroster Low Airflow
 

The front windshield defroster on my 2004 M-B C240 4-matic does not work well. The fan seems to be working OK. But the airflow is very slight.

I am thinking that either:1. the cabin air filter is partially blocked and needs be replaced with a new one or taken out altogether, or 2, there is a blockage such as leaves or mouse nests inside the air ducts or hoses that supply air to the defroster vents. If this is cause of the low air flow, what can I do to unblock the hoses? Can they be blown out by blowing air in the reverse direction,i.e., from the defroster vent to the cabin filter?

Any suggestions are truly appreciated.

Bad stepper motors, common issue on the w203. Read this thread.
https://mbworld.org/forums/c-class-w203/177068-noisy-air-conditioner-stepper-motor-replacement-clicking-hissing.html