Interior Heater

[why?]

yea, when you want to defrost you always need air from outside. inside air will always fog up your windows big time.

[advocate]

Originally Posted by why?

yea, when you want to defrost you always need air from outside. inside air will always fog up your windows big time.

I have never used new air from the outside...

Although to be honest the temperatures here in California are much much more mild.

What's always worked for me is to either point the air at the windshield and use the AC (so the air going to the windshield matches the windshield and no condensation is created) or the heater (so the air hitting the windshield is evaporated instantly). Both work well for keeping the windshield clear.