What jerry-rig fix for condensation on windshield?
 

Just wondering if anything simple can be done for the condensation on the windshield while using the a/c. I read another post where someone said to properly fix it, the whole dash would have to come out. But I wonder if some dash mounted deflector might help?

If you want a good laugh, I called MB USA one time about it. They said condensation on the windshield is completely normal. I said, "But it's so bad, I have to have my windshield wiper on". He assured me that's completely normal for ALL cars. I said, "You're saying it's completely normal, for ALL cars, on a dry summer night, to drive around with their windshield wipers on?" He said yes, completely normal.

What an idiot.

1991 300d, 90k

Does the condensation form on the windshield with the center button selected on the CC unit? If so, you can use the windshield defroster briefly to evaporate the condensation. I suspect the condensation only appears on the windshield and side windows when the humidity of the outside air is very high.

Your air pathways are not opening/closing correctly
 

When any appreciable condensation of this type appears on the outside of the windshield when you have the A/C setting pushed for cabin flow, without windshield flow (the button with down arrow on the lower half and the upper arrow muted) usually in the center of the selection row on climate control systems and others, and you can feel the heavy cold air flow from the vents by the windshield -- some of your baffles in the air flow control area are not opening and closing properly. Normally you can reach these on the right side of the under dash and correct the problem. One of the baffles may be stuck or otherwise inoperable and can be "fixed" to provide the proper direct flow into the cabin. Obviously, you still need heavy defroster air flow in cold weather coming from those windshield vents as necessary also.

I have the same problem on my 89 420SEL, which I plan to correct shortly.

BC

Mine does the same thing. My vacuum pod which controls the direction of the air flow from the vents I'm sure has a tear in it. It needs replaced and cold air will blow from the center vents only. The cold air on the windshield is what causes the condensation.

If you wanted a quick fix untill you replaced the pod - just buy some 3/4" Black foam weather stripping and run across the vent opening.