Windshield Won’t Defog: Common Reasons & How To Handle

Whatever the weather, you may have to fight foggy windows while maintaining a pleasant temperature inside your vehicle.

And fortune doesn’t smile on you if the windshield won’t defog and you can see nothing to drive on your own.

Densely fogging can form inside or outside automobile windows in bitterly cold weather, yet you have no idea how to get over it. Get inside this post to learn more.

Windshield Won’t Defog: Why?

Windshield Won’t Defog

Why won’t my windows defog? Foggy windows come from a large temperature and moisture differential inside and outside your car.

In the winter, the air outside is chilly and dry, yet your vehicle exudes heat and humidity (think of that moist breath against the cold glass).

The relative humidity drops when it’s freezing outside. Moisture in the air is less prevalent when temperatures are lower than indoors.

By wearing wet jackets or snow-covered boots, humans are contributing to the vehicle humidity. Also, warm foods, damp clothes, and heated bodies produce wetness.

On the morning commute, drivers may bring a coffee steaming mug. Then, when the temperature inside the car rises, the fog on the windows and windshield may become a severe obstacle to view the road.

This can be tough to repair if your automobile has poor insulation or a poor defrost system.

How To Defrost Foggy Windshield Inside And Outside Of Your Vehicle

We will have in-depth directions on how to defog inside of car and how to defog outside of car. Check out some of the quick steps on the specific conditions:

While Outside Is Warmer Than The Car’s Inside

The outermost layer of the windshield is where fogging would form in this scenario.

The wipers aren’t supposed to remove this completelly, and you might not be able to get out of the car to clean the windshield manually (in a rush or due to the severe weather).

As opposed to when it was cooler outside the automobile, you’ll want to turn up the heat inside now:

  1. You’ll need to turn on the windshield wipers and give them a chance to clear the glass before the interior temperature can match the exterior.
  2. To maintain a comfortable temperature while driving, turn the AC to its lowest level.
  3. Turning off the car’s recirculation feature will allow the exterior and interior to reach a more stable temperature and humidity level.

While Outside Is Colder Than The Car’s Inside

You might wish to up the air conditioner’s temperature in the winter or other cold seasons. This causes interior windshield fogging.

If you want to defog your windshield quickly and efficiently, you can do it with these quick steps:

  1. Set the thermostat in its highest level, as hot air absorbs and retains more moisture.
  2. Turn your AC on. The humidity will suck out the air as it travels over the coils.
  3. Turning off the recirculation switch will allow cooler, drier outside air into the vehicle.
  4. Open the windows a little to let the moist air escape, while the dryer one will enter.
  5. You can apply the defrost setting if your automobile doesn’t have a heater. This will dry the windshield’s interior by blowing heated air across its surface, eliminating fogging caused by condensation.

How To Prevent a Foggy Windshield?

After getting the answer to “why won’t my windshield defog?” Let’s explore some tips and tricks to keep them at bay:

Get Your Car’s HVAC System Inspected

Get Your Car’s HVAC System Inspected

A broken HVAC system might make it hard to remove windshield fog. Foggy windows are risky for you and other drivers.

Take your automobile to a repair shop if the defroster causes this hardship. The technicians get you covered by assessing and fixing the broken part.

Activate The Defroster When Warming Up The Car

Activate The Defroster When Warming Up The Car

Whenever you start your car’s engine, the defroster should be on.

Turn on the defroster the night before to erase the fog from the windshield. It works wonders if you want to heat your vehicle in the cold morning.

Wipe Your Shoes Before Entering The Car

Wipe Your Shoes Before Entering The Car

Before getting inside your vehicle, wipe off any snow or moist dew from your shoes using a dry rag. The likelihood of your windscreen fogging up due to high humidity inside the car will mitigate.

Activate Fresh Air Mode

Activate Fresh Air Mode

Ensure the recirculation setting is turned off and the fresh air mode is selected on your car’s HVAC system.

Otherwise, windshield fogging is more likely to grow because your car recycles moist and humid air.

Employ An Ammonia-Based Window Cleaner

Employ An Ammonia-Based Window Cleaner

This window cleaner helps the windshield inner buildup disappear. Use vertical or horizontal strokes while applying it, and reapply it often at will.

Apply Shaving Cream To The Windshield’s Interior

Apply Shaving Cream To The Windshield’s Interior

After putting shaving cream around your windshield’s interior with a clean and dry towel, eliminate the residue with another cloth. You can make a  protective film on your windshield to prevent fogging.

Keep The Window Open

Keep The Window Open

If your automobile tends to get foggy in the mornings, opening even one window would help. It’s also how to defog car windows in the morning.


How To De-fog Your Windows When It’s Cold Outside?

In winter, turn on your car’s heater to warm things up and your A/C to keep the air dry and clean your windows.

It does not just cool your vehicle; it defogs your windows in the winter, letting you drive safely even on frigid days.

When you do not like using A/C or it doesn’t work, refer to some ways to defog your windows without AC.

How To De-fog Your Windows When It’s Hot Outside?

As a temporary remedy, windshield wipers can clear the fog on the windshield outside.

Moreover, if you know how fog forms, you will know why keeping the window warm can prevent fogging. Redirect vents away from the window; don’t use defroster and raise the interior temperature.

How To Defog Windshields When It’s Humid?

Moisture is the troublemaker causing the frost on the inside the windshield and foggy windows. But how to defog car windows in humid weather? Here are three tips to have things done with ease:

  • Use windshield wipers to eliminate outside condensation. Using this part will remove the moisture barrier and balance the temperatures.
  • Turn off your car’s AC to keep the windshield always clear.
  • Alleviate summer windshield fog by washing both sides of your glass and using an anti-fog cleaner inside.

The Bottom Line

Even on days when there is no condensation, it is still essential to keep the glass as clean as possible. If your windshield won’t defog, apply the above tips to let fog-up go.

You’ll have better visibility and be less distracted behind the wheel when the windshield is clean.

It’s important to proceed carefully, though, or the condensation can worsen.

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