Very weak defrost and floor heat

[ksing44]

I have a 1995 E320. My fans seem to work fine. At least there is plenty of noise that sounds like the fans should be blowing air. I get the best flow from the side vents and I can feel that the air is warm, but there is just very little flow from the defroster and the floor vents. Even on high and with the controls set to all defroster, I don’t get much flow from the defroster at the windshield. I tried every possible setting for auto, max and low speed fan, as well as the different settings for all defrost, half and half defrost and floor, and mostly floor.

Let me see, I also have a rather loud slapping sound from something closing in the dash when I start the motor in the cold. I have had that for quite a while, even before I noticed the loss of the flow of air. I figured that was a fresh air supply vent slapping closed that limited outside air until the car warmed up a bit and maybe some foam padding had deteriorated. I did have decent air-flow in the past, even when I had the loud slapping.

Anyway, please help me understand what might be causing me to have low air flow from defroster and floor vents, even though I have a fan that sounds like it is blowing and the air seems to be warm. This is not a good situation going into a Pennsylvania winter. I just spent $1200.00 to get my front spring perches re-welded onto the car this week, so this is not a welcome surprise.

Thank you everyone,

Ken