The Garage Cars 101

Here’s How To Defog Your Windshield Fast

Let's get scientific about this simple task.
Here's how you defog a windshield
Even 996 Porsche 911 GT3s need to be defogged from time to time. Peter Nelson

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Operating a car mainly consists of simple, repetitive tasks. Unlocking it, turning on the ignition, using the turn signal (unless you drive a BMW), shifting it from park to drive (unless it has a manual transmission), and so on. Another one is maintaining visibility. You don’t need me to tell you how crucial it is to see clearly out of your car, and anything impeding your view of the road is a big safety concern.

In turn, it’s important to know how to properly defog your windshield. I won’t be spilling gallons of ink over this subject, because yes, it’s a simple task. But it’s definitely worth knowing the science behind defogging windows as it’ll help them clear up faster and make your journey as safe as possible.

Here's how you defog a windshield
Even race cars need a good defoggin’ depending on outside conditions. Peter Nelson

To get started, determine whether it’s hot or cold outside. If it’s cool, condensation is forming on the inside—meaning, cabin side—of the glass. Put the heat on full blast and allow the interior air to absorb moisture from the windshield. The next step is to dry out the interior air, so follow up with some air-conditioned cool air that’s drawn from the outside. Make sure recirculation is off if you’ve got it. Finally, if it’s not too cold outside, crack the windows to help equalize temperatures.

Fun fact: Some cars will automatically turn on air conditioning if you select the air to hit the windshield. Older Mazdas do it.

If it’s hot outside, clear away windshield moisture by simply turning on your wipers. To keep it away, consider cracking the windows or turning up the temperature on your climate control.

Here’s a quick tip to prevent condensation from forming in the first place: If your last trip was the night before, take 20-30 seconds to let all that warm air evacuate out of the car and equalize with the outside temperature.

To keep moisture away even more, or at least make windows defog faster, consider coating them with a proper solution. Avoid Windex and other conventional glass cleaners. They often leave a residue on automotive glass, even if they don’t on a house’s windows. Stoner Invisible Glass Anti-Fog is good stuff that we’ve used in the past. Also, it’s a good idea to clean your windshield regularly with a good solution.

Defogging a windshield is a very simple task, but one worth doing as quickly as possible.