Window Fogging in Winter W123
 

Does anyone experience window fogging (the rear ones mainly) when the heat is on and it is 32F or lower? Normal, BiLevel and defrost modes remove moisture very well but the AC compressor can't work below 36F. Damp New England cold. Most annoying in sleet/snow. Perhaps there is another issue with my HVAC? Or is it the limitations of the early climate control systems. '84 300D. Not a problem in my 190.

is there any moisture in the trunk?"

Minimal. Why do you ask? Rear window seal?

You beat me to it, additionally, are the mats or floors wet?

The floors are fine. I will replace the infamous seal. Why does this affect the windows as much as it does? Many thanks.

Cowl drains clean and clear? Or water puddling in the intakes adding to the dampness inside the car? Wet dirt or pine needles in there?

http://www.peachparts.com/shopforum/diesel-discussion/234009-w123-cowl-drain-grill-removal-wiper-arm-linkage-quick-fix.html