Credit: Kenneth Cheung / Getty ImagesCar windows fog up on rainy days from high humidity and condensation. You need to clear those windows, fast, or poor visibility could put you in a dangerous situation. So you press the defogger button—also known as the defroster—and the fog disappears like magic.It may seem miraculous, but a car defogger is actually very simple. Here's how the window defogger in your car works and when and how to use it.How The Window Defogger WorksYour vehicle's window defogger clears fog and condensation with heat. The front defroster releases a blast of warm air right under the windshield, drying any condensation and melting snow and ice. Most cars also activate the A/C while the defogger is running, which removes humidity from the interior of your car.AdvertisementAdvertisementThe rear defroster works differently. Rear windows have a grid of electric wires that heat up when you press the button. You've probably noticed that fog and snow disappear along the wires first, and then slowly melt from the rest of the window.How To Defog Car Windows QuicklyYou need a clear view of the road to drive safely, so it's always best to defog the windows before you start driving. But if your windshield fogs up while you're sitting in traffic, you can defog the windows within a few minutes. At that point, your engine should be warmed up enough that the defogger can work effectively. Turn the front defogger on max or high so that you get maximum air flow. If your car doesn't automatically turn on the air conditioning, press the A/C button as well. It may seem counterintuitive to have A/C and heat running at the same time, but you need dry air to remove moisture and humidity. Turn your windshield wipers on as well if you have condensation on the exterior of the windows.Frost and ice take much longer to clear from windows, so you should do that from your driveway. Start the car about 15 minutes before you plan to leave. Turn on the rear defroster right away, but let the engine heat up for a few minutes before you turn on the front defroster. Scrape off what snow and ice you can, then turn the windshield wipers on once they are free of ice. You can safely drive once all the ice, meltwater, and fog have cleared from your windows.Should You Use Warm Or Cold Air To Defog A Car?Most modern cars let you choose whatever temperature you find comfortable, even when you have the defogger running. The defogger can work with both warm and cool air. This is because you're blowing dry air onto your windshield either way. However, warm air can absorb more moisture than cold air, so you may want to turn the temperature up a little. In most cases, warm, dry air removes moisture from the glass on your windshield more quickly.AdvertisementAdvertisementIn winter, your windshield can fog up temporarily while you're running the heater because of condensation. Condensation is caused by the warm, humid air inside your car hitting cold glass. The fog should clear as the glass warms up and dries. Reducing the humidity inside your car with the A/C also helps.Read the original article on Southern Living