When you drive in the winter, you often have to deal with a foggy windshield. First, let’s define the difference between fog and frost. Fog is made of tiny droplets of water that have been condensed onto the windshield. You’ll find this anytime you have a difference in temperature between two sides of the glass. The fog forms on the warmer side, which is the inside of your car. Frost, on the other hand, is a layer of ice. You’ll see it most commonly on the outside of your car, and it’s what you scrape off with an ice scraper. In very cold weather, the fog on the inside of your windshield can freeze, giving you frost on the inside. This might throw a lot of people off, but the truth is, to defog in cold weather you have to turn on the heat AND the air conditioning. Yes, you can do both at once. Put the heat on the hottest setting and then turn the AC on. Make sure the air is getting blown full blast on the windshield and turn recirculation off. Turning off recirculation helps because you’ll be pulling in dry air from outside instead of recirculating the slightly humid air inside. To prevent foggy car windows, which is caused by moisture inside the car, keep the inside of your car dry. If you’ve tracked a lot of snow and slush into the car, clean it out. Start warming up the windshield before it’s time to drive and put the heat on the windshield while you brush and scrape the outside. Finally, consider cleaning the inside of your windshield with a glass cleaner. Don’t use your hands or those fast-food napkins you found under your seat. Skin oils and miscellaneous grease and dirt will only make the problem worse.
