How to defog the windows in your car

Can't see all of a sudden? Our quick guide on defogging your car windows

how to defog car windows wikipedia commons  foggy windshield

We’ve all been there. You’re driving along, probably through some sort of inclement weather and then — bam — out of nowhere, your windows begin to fog up from variances in temperatures and humidity levels and you can no longer see.

While foggy car windows are not the end of the world, they create an unsafe situation and can completely inhibit your exterior visibility while driving. There are several reasons as to why car windows and windshields might fog up and, again, it’s all dependent on the weather conditions.

For instance, if you’re driving through a cold, wintry climate, windows fogging up from the inside might occur quite frequently as the cold ambient temperatures create the perfect breeding grounds for condensation while occupants keep warm on the inside. The result heats up the moisture inside the passenger cell along with the air. When that heated moisture hits the cold glass, condensation or fogging occurs.

Alternatively, if you’re driving through humid, summery conditions, passengers might have the air conditioning engaged to keep the interior cool. This ultimately also cools the vehicle’s windows from the inside, causing them to fog up on the outside. But thankfully, this can easily be remedied through the use of windshield wipers or by simply rolling the windows down, and then back up.

If your windows fog up from the inside, don’t panic! Here are a few basic and easy steps that can help you defog your windows safely and while on the go.

At first, it might seem like a good idea to simply wipe the condensation off your car windows with your bare hands. While you can do that as a temporary measure just to be able to see again, particularly in front of you on the windshield, we actually don’t recommend you do that.

Wiping a foggy window with your bare hands can actually worsen the situation by smearing whatever oils and contaminants caught on your hand — such as skin oils and other dirt. When the condensation returns, it will be harder to see than prior to wiping it with your hand. Here’s what you should do instead.

Turn on your air conditioning

Whether it be in the dead of winter when it’s cold outside or in the heat of the summer, your car’s air conditioner does more than just cool the interior air. It doubles as a dehumidifier. On most newer cars, interior HVAC systems with an “automatic” function typically keeps the AC compressor on by default for the most optimal interior comfort. That said, just enable the window “defroster” mode, as depicted by the icon below.

how to defog car windows windscreen defrost

If you don’t have automatic climate control, make sure the AC compressor is engaged by pressing the button or flicking the switch on your center console with “AC” labeled on it until it’s indicated as on. The “defroster” mode sets the blower fan to its max setting, vents actuate to channel the airflow to the outlets on the dashboard, aimed toward your windshield. As long as your car’s HVAC system and AC compressor are functioning, your windows should defog themselves in no time and on-the-go, with the help of the climate control system. No need to pull over and give all your windows a quick wipe-down.

What to do if your car’s AC is malfunctioning

Do you have an older car or drive one with a disabled AC compressor? No worries. We totally understand; AC system repairs can get costly really fast. You can still use the HVAC system and heating to clear your windows in the winter. But if you’re driving on a hot and humid day in the summer, this option sadly won’t work, especially if there’s no cool, dry air available from a malfunctioning AC compressor, which also prevents the evaporator from functioning.

That said, we recommend keeping a roll of paper towels, napkins, or a set of clean rags inside your car and within easy reach. That way, you can avoid using your dirty, oily hands on your windscreen and windows when wiping off condensation.

If you do need to exert some physical and manual labor to clear up your windows, it’s best to pull over on the side of the road to avoid any accidents.

And the best way to keep your windows from fogging up… ?

Aside from just keeping the AC compressor running whenever you’re using your car’s HVAC system to keep the interior air dry, always keep your windows extra clean. You can use a generic window cleaner, such as Windex. But if not wiped away properly, Windex can leave behind residue, which also causes smearing and streaks when windows fog up, making it even more difficult to clean and see through.

That said, we suggest using dedicated car window cleaner, such as Rain-X or Invisible Glass window cleaner. They’re specially formulated to prevent streaks and windows from fogging from leaving minimal residue. Those can easily be picked up at any of your local auto parts or department stores.

If you want to take an extra step, you can also treat your windows with a product like Rain-X glass cleaner and water repellent. This leaves behind a clear, thin film on your glass, preventing condensation from forming.

And that’s it! Fogging windows is a very frequent occurrence, so these quick tips should help you defog them in a safe manner.


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