Why do car windows fog up on the inside and how to fix it (2023)

Misted car windows are not uncommon, especially in winter and when the humidity is high. It is worth figuring out why this is happening before you start troubleshooting as it can cause dangerous inconveniences as you will not have good visibility when driving causing a high risk of an accident.

It is important to understand that the quality of the windows installed in cars varies. Depending on the brand and model, the big difference can be the substances with which the windows are treated and if they have the property of being electrically heated, this can be enough to rarely see a fogged window.

If the car has an electric windshield heater, this will help dry the windows quickly without turning on the heater or air conditioning. In addition, this function quickly frees the glass itself from ice and snow in winter.

You can add this option to "must have" when you want to buy a car, but newer cars already have this option as standard.


(Video) Ugh! Why do my car windows keep fogging up?!

What causes car windows to fog up?

As I said above, you will most often notice steam on car windows in winter when it rains, when it is foggy and when the humidity is high.

In these conditions, visibility is usually poor and the risk of an accident is significantly higher, since all windows usually fog up. It also happens that the reason for fogged windows is not only the weather.

In any case, you need to know what to do in this situation and what to do so that the windows do not sweat. Let's see what the causes are.

colder temperatures

In winter, car windows mist up because condensation forms due to the interaction of warm inside air and cold outside air. This condensation is deposited on the windows and leads to fogging.

High humidity

Another common cause is when it rains. This happens because the humidity in the cabin rises sharply. In addition, moisture begins to actively evaporate from the driver's or passenger's wet clothing, as well as from wet mats, after the heater is turned on.

(Video) Never Get Foggy Car Windows Again

Problems with the cabin filter

If the cabin filter hasn't been changed for a while, it will contain dirt and debris, making it difficult to add air from the outside.

Also, its defects, model discrepancies or errors in the installation of the cabin filter lead to the fact that moisture and dust are not properly absorbed, and the result is fogged windows.

Air recirculation mode is switched on

Most cars these days have the option of recirculating the air from the cabin. This option prevents fresh air from entering the cabin from the outside. This function is useful in certain situations, as it prevents dust and unpleasant odors from entering the car from the outside.

Switching on the air recirculation mode allows the interior to be warmed up or cooled down more quickly, but the windows will also mist up. As a simple solution, just turn off the recirculation.

There are some cases where this function has errors, such as: B. a stuck valve, and does not let outside air into the cabin, but these situations are rare.

coolant leaks

If the heater core or a branch pipe leaks, the coolant can leak into the passenger compartment and evaporate. Because of this, the moisture on the windows can be oily.

(Video) How to Stop Car Windows from Steaming Up

If you discover leaks on the driver's and front passenger's side, you must always get to the bottom of the cause quickly, because there may be serious faults in the cooling system.


Alcohol fumes exhaled by a person who has been drinking causes car windows to fog up.

How to prevent car windows from fogging up?

The first thing you should do is to know the exact cause of fogged car windows and then fix it. Of course, you can always wipe the glass, but this only takes time and does not solve the problem, it only allows you to get rid of the consequences.

You can also turn on the car's ventilation to dry the windows, but as a disadvantage you will have to wait a long time for the engine to warm up, especially with a cold start.

For better results, you can turn on the air conditioner, which will give faster results in removing the moisture, but as a disadvantage, fuel consumption will increase and the resources of the air conditioner will decrease.

I have compiled a list of tips below that are effective in preventing car windows from fogging up. But before using them, you should wipe the windows from the inside with a paper towel or a dry cloth to remove moisture and dirt.


  • Lemon. Cut it in half and wipe the glass with it. The fogging will stop and you will also get a pleasant smell in the cabin;
  • Soap. It doesn't matter what kind of buoyancy it is. Simply apply to the surfaces of the windows, then wipe the entire area with a dry cloth and then a paper towel. You can also use shaving cream here, it works the same way, but thanks to its semi-liquid state, the process is faster
  • regular salt. Rub the glass surface with it and put the salt in small bags on the center console or the dashboard as a precaution;
  • Alcohol solution in glycerin at a ratio of 1:20. Treat the surfaces with a clean cloth or sprayer, then wipe the glass.

In addition, to prevent the windows from fogging, you should regularly check the car's ventilation system, heater and fan, etc., and most importantly, change the cabin filter in time. Also, don't forget to turn off the recirculation.

Another way to prevent window fogging is to do thisglue a special film.Such a film also has the property of preventing moisture accumulation.

An anti-fog spray for car windowsis also a great solution. The composition is applied to windows that have previously been washed, dried and degreased. In practice, the solution is effective, but one application is enough for only 10-15 days.

You can also make your own anti-fog solution by mixing ethyl alcohol with glycerin. The ratio is 20:1 where 1 is glycerin. The mixture is then placed in a spray bottle for easier application.

How to properly remove moisture from the windows in the car

  • If it's winter, the first thing you need to do is clear the windshield and side windows of ice and snow. As long as the ice is lying on the glass, it will sweat from the inside, even if there is a strong draft of warm air.
  • In order to then free the windows from fogging up, nobody should be in the car. Turn on the heater and wait for it to blow warm air.
  • Next, turn off the recirculation if it's on to allow fresh outside air to flow. Try directing the air towards the windows by adjusting the air deflectors.
  • If it's relatively warm outside and it's raining, turning on the air conditioner will remove moisture better.
  • At the same time, it is not necessary to warm up the engine, because in this case the temperature of the air blown on the glass will not affect it much.
  • After the windows have been cleaned, you can switch on the air circulation so that the windows don't sweat any more while driving. However, increased humidity in the cabin can cause the windows to mist up again. In this case you have to try other possibilities.
  • As for the rear window, the matter is simple, just turn on the heating.


As you can see, an important aspect of ensuring that the car windows do not fog up due to the weather conditions inside is to have the most efficient ventilation in the cabin. Sometimes, instead of waiting for the heater to dry out the moisture, it's better to open the windows slightly.

The cabin filter must be correct and also changed in good time. If you are unsure of its quality, it is better to buy a more expensive activated carbon filter than cheap aftermarket filters. The filter itself must also be installed correctly.

(Video) This Simple Hack Will Keep Your Car’s Windshield Fog Free This Winter, But You’ll Never Believe What

Also, do not leave wet things such as shoes, jackets, etc. in the car, as moisture will settle on the windows as they dry. It is also recommended to drain the water and wipe the rubber mats thoroughly. Fabric mats must be removed from the vehicle and dried separately.

If the car has been exposed to high humidity for a long time, the entire interior must be dried. This can be done by leaving the car in a warm garage or parking lot for several days with the windows slightly open.

If the windows mist up while driving and the heating and/or air conditioning system cannot finish cleaning the windows, it is recommended to drive with the side windows open. Even if it's hot in the cabin and cold and humid outside, it's better to open all the doors for at least 5 minutes after driving to get some fresh air in the car.


1. How To Avoid Fog Inside The Car During Rainy Seasons || Defog Windshield
2. How to Prevent your Windows from Fogging Up
3. Why Does The Windshield Fog Up In A Car-Easy Explanation
(Helpful DIY)
4. How to Stop Car Windows Steaming Up
5. How To Remove Fog | How to Stop Car Windows from Steaming Up | Car Problem | Simple | VBO Life 2020
(VBO Life)
6. Wipe your Car Windshield with Shaving Cream and WATCH WHAT HAPPENS 💥
(Smart Fox)
Top Articles
Latest Posts
Article information

Author: Kerri Lueilwitz

Last Updated: 04/08/2023

Views: 5288

Rating: 4.7 / 5 (47 voted)

Reviews: 86% of readers found this page helpful

Author information

Name: Kerri Lueilwitz

Birthday: 1992-10-31

Address: Suite 878 3699 Chantelle Roads, Colebury, NC 68599

Phone: +6111989609516

Job: Chief Farming Manager

Hobby: Mycology, Stone skipping, Dowsing, Whittling, Taxidermy, Sand art, Roller skating

Introduction: My name is Kerri Lueilwitz, I am a courageous, gentle, quaint, thankful, outstanding, brave, vast person who loves writing and wants to share my knowledge and understanding with you.