foggy windows

[Snoopy]

Hi. All winter I've been struggling with foggy front windows. The fog is so 
strong that even after blowing everything towards windshield for an hour there 
are still small drops of liquid in the corners. It even seems that the more 
you blow, the worse it gets. I thought that it is usual winter stuff (you get 
snow inside, then evaporate it by heating, etc.), though I haven't noticed it 
during previous 6 winters. But now it is spring here, temps are +5-10 C, and I 
still sometimes get the fog.

I checked the famous recirculation flap, it works fine. No errors on AC diag. 
Checked under the carpets, everything seems dry. Tried to clean the windshield 
properly a few times - nothing. My guess is that the heater core is leaking 
just a little bit, and during heating it transfers coolant onto windows, 
that's why it's hard to get it clean/dry. Is it possible?


P.S. I even tried to taste this stuff, but no usual sweet taste. Yes, I know, 
it may be poisonous, but what can you do :)


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A100 Avant '90 2.3