Why Does the Inside of My Car Window Freeze?by Liz Fremont
Ice or frost build-up on the inside of your car windows can be annoying and may interfere with your visual field and safe driving. Fortunately, you can take steps to remove this condensation quickly and prevent it from occurring in the first place.
Ice and fog form on the inside of car windows when moisture in the car evaporates, condenses on the glass and then freezes as the car cools. Warm, moist air exhaled by the car's occupants and melting snow brought into the car on boots and clothing all contribute to moisture build-up inside the car.
Turn on the car heater and set it to high. Allow the windshield to warm for several minutes. The ice or fog on the glass will dissipate. Wipe off the condensation from the window glass using a clean, dry towel or cloth. Turn on the air conditioner briefly to remove humidity from the vehicle cabin. Don’t re-circulate the air except to initially warm up your car.
Leave a window cracked open slightly overnight or when you arrive at your destination to help prevent windows from icing up. Ice sticks to dust and residue on the window glass so keeping your car windows clean will minimize this problem. Knock snow off of your boots or shake water off of your raincoat entering the car; the less moisture in the car, the better. You can also use a spray-on product such as Rain-X Interior Glass Anti-Fog to help prevent ice and fog buildup on the window glass.