Frosty the Windows

[Pacfanweb]

You may well have a water leak inside the car. Check under all your mats and see if there's any dampness.

 

[Yuriman]

Just as a point of reference, the windows in my G1 Insight will start to fog up after a few minutes on a really cold day unless I have external air coming in on high or a window cracked, and almost immediately if I have a passenger. In my work van, the volume of air is sufficiently large inside that I've not seen any of the windows fog, even with the climate control turned off.

 

[Toastedlightly]

Try this (if it is still happening). Start the car and turn the heat to defrost and then get out and let it warm up (do on a dry day). Let it warm up and see if you get frost inside the window. That would indicate a moisture source such as a leaking heater core or other inside the car.