Mercedes: 1990 MBenz AC Problem, mercedes benz 300d, benz 300d

Question
When I turn on the Fan in my 1990 Mercedes Benz 300D, 2.5 Liter Turbo, I hear a flapping sound coming from the air vents.  It appears to come from the AC Box under the dash.  It happens when the AC is on and when it is just moving outside air.  When the AC is on, I don't get a full cooling effect.  What is the problem and how can it be repaired?

Answer
Have you replaced both filters???
The flap noise you describe sounds like normal air blend door operation.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1990 Mercedes Benz 300D Turbo 2.5
Part: ACC Cabin Filter
 Note:  2 per car
Also referred to as a combination filter, cabin filter or
pollen filter.  
  
R2060-53915 ACC Cabin Filter ACM IN STOCK $22.05  
  
R2060-138299 ACC Cabin Filter Bosch IN STOCK $22.05  

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