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How to Defrost Car Windows

A windshield covered in ice.

Wondering how to defrost car windows? It’s something everyone starts to think about when the weather gets cold and a layer of ice crystals coats your car windshield in the morning. Here’s what you need to do to safely defrost your car windows.

A Note of CautionIce on a Windshield

First, this is what not to do — because people try it every year. Do not toss hot water on your ice-cold windshield! This might seem like a good idea, but it will ruin your day and your windshield. If you suddenly douse cold glass in hot water, it will very quickly expand and then contract again due to the cold air temperature. This can cause the windshield to chip or crack, which means you may end up with a broken windshield to fix. Instead, follow the steps below to defrost your car windows safely and quickly.

1. Turn on the Engine and Crank the Heater

Start your engine and set the air to the windshield defroster setting. Turn the heat all the way up. It will take a few minutes, but the air will gradually get warm. You want heated air circulating through your car as soon as possible, even if it’s only lukewarm, because it will absorb the excess moisture trapped in your car. If you were paying attention in science class, you’ll remember that hot air can take on more moisture than cold air.

2. Press the A/C Button

Yes, really. It seems counterintuitive given that we just said to turn on the heat, but you want the air conditioning on even though the temperature is set to high heat. Turning on the A/C lets the coils in the system help dry out the air in the cabin of your car even more.

3. Set the Air Recirculation to Off

You want to bring in the cold winter air because it’s already nice and dry. It’s another way to help dry out the moist air trapped in your vehicle. And if you notice that air doesn’t seem to be coming out of a vent even though it’s open, you may be looking at a malfunctioning air door actuator in need of replacement.

4. Crack Your Windows

Open your windows just a smidgen. Again, this lets in the cold, dry outside air while letting out the warm, humid inside air. You should be seeing a pattern here.

5. Watch the Ice Melt

Once you’ve followed these steps for how to defrost car windows, you’ll quickly start seeing clear spots in the built-up frosty layer, and the ice eventually will melt fully. Make sure you wait until you can see through your windows entirely before driving off. Don’t ever hunch over the steering wheel and try to drive with just one tiny clear circle — you need full visibility to be safe, and with this method, it won’t take long.

Check out all the windshield deicing products available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information about safely defrosting your windshield, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Nicole Wakelin View All

Nicole Wakelin covers the automotive industry as a freelance journalist for a variety of outlets. Her work includes news pieces, podcasts, radio, written reviews, and video reviews. She can be found in The Boston Globe, CarGurus, BestRide, US News and World Report, and AAA along with lifestyle blogs like Be Car Chic, The Other PTA, and She Buys Cars. She is active on social media with a large following on both Twitter and Instagram and currently serves as Vice President of the New England Motor Press Association.

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