You might have a leak in heat exchanger for the heater. Do you loose coolant? Do you smell anti-freeze inside the cabin?

 

Hondas generally do fog up more than other cars. Not sure if it has anything to do with how tight the interior is when the doors are closed and windows up. I remember my dad's 1987 Accord LX-i did the same thing, my Prelude does as well, and I wondered why when my Mom's 1985 Buick Regal never did......

BUT, Honda also has the best defogging ventilation system on the market as well. When it gets foggy, I just push the defog buttons (front and rear, A/C engages automatically), fan all the way up on high (#4), and adjust the temp for my comfort.... in about 2 minutes or less, every window in the car is completely fog free. Then I turn the fan down to low to keep it on the rest of my trip.

 

yeap.

 

Although this may be an old post already, I wanted to ask simsurfer if he has ever messed with his doors (for example did you pull of the plastic when changing a speaker or fixing a window maybe)?

Althoug already mentioned: Windex is the best thing for foged up windows, because if you have not noticed, after cleaning bathroom windows with windex you have less fog or no fog on them, but if you wipe the mirror with a towel it just makes it worse. So dirity towel or dirt equals more fog to collect on! So clean them with windex first, then put rain x on, and rent a motel, then you should be fog free...