Why do my windows fog up
when the defrost is on?
Most likely, your “air recirculate” button is on. Turning it on recirculates the air inside of your car rather than only using fresh air from outside. The best time to use “recirculate” is in the summer, when you want to quickly cool down the inside of your car with air conditioning. Then it will recirculate the air that has been cooled already. Once the car is cool, the recirculate should be turned off to pull fresh air into your car.
In the winter, this really works against you! It recirculates the moisture from the people in your car and fogs up the windows (almost like that school bus full of kids). Turn off the “recirculate button” and it will pull in fresh, dry air from outside of the car. This air won’t fog up your windows so much!
If you smoke in your vehicle, you should never use the recirculation feature while smoking!