this is also happens to me (but not as bad) when i run the AC at lunch and drive home with the windows down but only when i turn the AC/fan off. if i keep the fan running it never happens.

 

rub a bunch of spit into the inside windshield--lol j/k ...but works for divers....

 

Please provide a point of reference as to why a dirty cabin filter would not have a darn thing to do with window fog. Just because it has never happened to you doesn't mean that the problem is ruled out.

The vent where the cabin filter is housed allows for ventilation. When a cabin filter is clogged, you have less ventilation. Without proper ventilation, you can get humidity build up. This contributes to fog inside your windows.

Its the same principal as when you put an AC system on recirculate with the AC off and your windows fog up, or when you turn your car off and you sit in it on a humid day and your breath fogs up the windows.

Try googling dirty air filter and window fog and get back to us.

 

So I was just driving outside with my windows down. It is about 71 degrees here in NJ and low-mid humidity. It's actually very nice out. As some of you suggested, I turned my defogger temperature up. I decided since it was 71 out, that I should set my defogger to 71 as well. As it turns out, my windows didn't fog up. I could see a slight fog but it was barely noticeable. I guess the problem was me setting the defogger way too cold. Hopefully this will work when its 80 degrees out and higher humidity. I'll have to report back on what happens with different temperatures.

Thanks for everyone's help. I think I'm going to change my cabin air filter as well, it cant hurt. Plus sometimes I feel like there is a nasty smell when I first turn the car on so I'm sure the cabin filter will help with that.

 

KAHBOOM had it nailed in his first post. Cold air is definitely the worst way to clear any condensation/fog. Moisture will evaporate off the inside of the wind shield more quickly as the temp increases. Just like a hair dryer on cold will take much longer to dry your girl's hair than a hot hair dryer would. Not sure about the cabin filter, but that's a good reminder. I need to do mine! haha. Good luck