Skip to Content

How To Defog Your Windshield Without Using The Heater

Disclosure: We may get commissions for purchases made through links in this post.

Windshields can fog because of different reasons, including significant heat, humidity, and condensation. Driving with a frosted windshield can become hazardous, especially if your car’s built-in heating system is malfunctioning. So how can you defog your windshield without the heater? We researched for your convenience, and here’s what we found.

Mix two parts of rubbing alcohol and one part of water into a spray bottle. Then, spray the solution on a frosted or fogged-up windshield to restore the glass' clarity. The results should appear within a few seconds after application.

It’s also important to know how a windshield frosts or fogs up. Identifying these sources can help prevent the issue from surfacing. Continue reading as we talk about why your car’s windshield becomes foggy. We’ll also tackle the method to defog a windshield without a heater in greater detail.

Close-up of the hands of the driver on the steering wheel of a car with fogged windshield, How To Defog Your Windshield Without Using The Heater

Why Does The Windshield Get Foggy?

Fog on windshields can surface from different sources. Some of the causes of foggy or frosted windshields are:

Inclement Temperature

Whipers are pushing snow away form the steamy windshield

Take note that water vapor condenses when the airborne moisture in the glass and inside the vehicle is colder than its dew point, which is the temperature at which water vapor condenses. In turn, if the heat inside the car's cabin is higher than the windshield, the glass will fog up.

Aside from turning on the heater for the automobile’s interiors, the number of passengers may also contribute to the increased cabin warmth. Body heat and damp breathing can enhance the moisture content inside the car, leading to increased risks of the windshield fogging up.

Filthy Windshield

Unclean particulates like dust, dirt, smoke, and chemical residue can introduce and aggravate windshield fog. It’s because the filthy substances can create additional space for moisture to adhere onto the glass, allowing the windshield’s ability to defrost longer than usual. Therefore, having your windshield clean can help reduce the occurrences of fogs and frosts.

Read our post on how to clean a car’s windshield to learn more about keeping the glass spotless.

Check out this windshield cleaning kit on Amazon.

Dirty or Faulty Filters

Many automobiles come with filters that help prevent dust, pollen, and other particulates from invading the cabin. If these components become dirty or malfunction, they might let in more dirty substances into the vehicle’s interiors rather than keeping those things out.

In turn, the dust, dirt, and debris can latch onto the windshield, causing it to become filthy. With the additional filth on the glass, moisture can thrive on it, leading to the material fogging up. Change your car’s air filter at least once per 15,000 to 30,000 miles to ensure this part remains clean and functional.

Check out this cabin air filter for cars on Amazon.

How Do I Defrost My Windshield If The Heater Is Broken?

smiley face on foggy windshield

A water-and-rubbing alcohol mixture can help defrost from a windshield without you relying on the vehicle’s heating unit. You only need to mix one part water with two parts 70% rubbing alcohol. Then, pour the solution into a spray bottle. Apply the concoction onto your windshield, and it should melt the frost within seconds.

The reason behind this solution is rubbing alcohol's freezing point of -128 degrees Fahrenheit. Therefore, spraying the alcohol-and-water mixture on your car’s windshield prevents it from fogging or frosting.

But take note that this solution is only for the short term. The glass may fog or frost again when the mixture’s efficacy wears off. In turn, you may still want to ponder upon having your car’s heater fixed if it’s broken or use longer-term solutions like changing your windshield washer fluid.

Check out this windshield washer fluid on Amazon.

If your car has a clogged windshield washer, read our guide for you to solve this problem.

How Do You Keep Your Windshield From Fogging Up Without Heat?

Different techniques are available to prevent a windshield from fogging up. Some of these methods are:

Turn Off Cabin Recirculation

The air recirculation button in many vehicles cuts off outside air while redistributing the air in the cabin. Turning on this feature can help reduce or eliminate outdoor air pollution from entering a car’s interiors. However, it also means that moisture-rich air will remain in the car and will eventually latch onto the windshield.

If fog starts to appear on the windshield, take this chance to turn off the cabin recirculation feature. The control for this feature usually rests on the car’s dashboard or central command panel. It should look like a tiny car with a curved arrow. Then, roll down your windows slightly if you can.

Apply Anti-Fog

Some anti-fog solutions for windshields may only need a few applications once every three to four months. In certain cases, you may need to reapply these substances once per month. However, these products might be more challenging to apply than the rubbing alcohol mixture mentioned in a previous section of this post.

Check out this anti-fog on Amazon.

Use a Chalkboard Eraser or Magic Eraser

Chalkboard and magic erasers are reasonably inexpensive solutions to remove excess fog and moisture from a windshield. But be wary as some of these erasers can be quite abrasive. If you put more pressure on these items than necessary, the material's roughness can cause scratches to the glass.

Check out this product on Amazon.

Follow these steps if you wish to continue with this technique:

  1. Rinse the windshield to remove loose dirt.
  2. Let the glass dry and lightly apply the chalkboard or magic eraser with your preferred windshield cleaner.
  3. Remove the residue by wiping the windshield with a microfiber towel.

Here’s a video to help you see how to complete this process:

Apply Shaving Cream

This relatively unconventional solution can help remove and reduce fogging instances on windshields. It’s because many shaving creams have similar chemical makeups as many defoggers.

The steps for this procedure are:

  1. Apply a decent amount of shaving cream onto the windshield.
  2. Use a microfiber cloth or towel to spread and wipe the cream on the surface.

The video below can also show you how to do this technique:

What Happens If You Pour Hot Water On A Frozen Windshield?

Hot water in pot to solve ice problem on car window

Pouring hot water over a frozen windshield will melt the ice. But it might also aggravate issues like spreading existing chips across the surface or introducing new cracks to the windshield.

But the glass may not encounter any problems after pouring the hot water, depending on certain factors. For instance, the car manufacturer may install a sturdy windshield that prevents it from cracking or breaking from extreme temperature changes.

However, in many cases, pouring hot water on frozen glass can cause the material to shatter. It’s because the material might not have sufficient durability that to prevent it from cracking or shattering.

Watch the video below to see one car owner pouring boiling water on his vehicle’s windshield to see the effect:

Final Words

raindrops and street light bokeh on wind shield

A temporary solution to defogging a windshield without depending on a car's heater is to create a water and rubbing alcohol mixture. Spray the solution onto the windshield to remove built-up fog or frost from the glass. Still, you should think about using long-term windshield winterizing solutions to help significantly reduce repeated applications of this DIY anti-fogging concoction on your car’s glass.