As a driver, it’s necessary and useful to know how to defog a car windshield.
Especially during the winter and rainy seasons when the car fogs up almost instantaneously when you get in it.
A fogged-up windshield and windows mean much less visibility making it a serious safety risk. One more very good reason to know this.
This article will show some simple and easy ways to defog a car windshield. Besides this, you have a video at the end of the article that you can also watch on our YouTube channel.
WHY DOES THE WINDSHIELD FOG UP?
The main reason for fogging up is the difference between the outside temperature and the temperature in the passenger cabin.
Also, one less common reason is moisture within the passenger cabin that can be caused by leaks, a bad heater core, or else.
If your car fogs up often, you should also check, just in case, if the interior (mainly the carpets) is dry.
For more information on heater core problems, click here to read a separate article on that topic.
HOW TO DEFOG A CAR WINDSHIELD?
1. KEEP THE WINDSHIELD CLEAN
Keeping the windshield clean is one of the most important tips.
Why? Well whatever method you use for defogging the windshield, it will take much more time when it’s filthy.
A greasy and filthy windshield is an absolute magnet for fog. It fogs up much faster and it’s much harder to get rid of the fog later.
Opposed to that, a clean windshield means less fog to start with and much less time for defogging.
From experience, a clean windshield will defog with some of the methods we’re going to show you in something like 30 seconds but with a filthy windshield, it takes a couple of minutes at least.
This tip also applies to all the windows in the car.
If you want to see how to properly clean your windshield, click here to watch our video dedicated to that topic.
2. PROPERLY SET THE CABIN VENTILATION
You can’t learn how to defog a car windshield without knowing how to properly set the cabin ventilation.
This is a key factor and almost all cars have a specific setting for defogging, drying, or defrosting the windshield.
If you have a manual AC, then turn the ventilation flow towards the windshield, turn on the heating and the blower. Best turn on the blower to maximum power.
It would also be good to shut the side vents as you get more airflow to the windshield.
For automatic climate systems, most have a defrost/defog setting or button for this so by pressing it the climate control will defog the windshield as fast as possible.
3. TURN ON THE A/C
Turning on the AC or climate compressor alongside the ventilation and heating is one of the most effective ways to defog the windshield and the windows.
This tip is mainly for manual climate systems as automatic ones usually do this on their own, so to say
So, besides turning on the blower and heating, turn on the AC compressor.
As you’ll see, in most cases, the defogging will happen much much faster than with just the blower working and you’ll get a better end result.
Most people don’t know about this tip as it’s common for a manual AC compressor to stay off in colder weather.
4. SLIGHTLY OPEN THE WINDOWS
If you don’t mind the breeze and cold, a good way to defog the windshield but also the other windows is to open them a bit.
Not all the way but just leave a slit opening.
By doing this, you let some fresh colder air inside which makes defogging easier and prevents further fogging up.
When talking about how to defog the windshield, this is more of a secondary help. It’s most effective in a combination with other methods like turning on the AC for instance.
5. WIPE THE WINDSHIELD WITH A CLEAN CLOTH
The last method we’re going to show you is effective but somewhat crude.
It’s mostly used when the ventilation system, for some reason, doesn’t work or you don’t have time to wait for defogging.
Nothing special to explain here, just grab a cloth and wipe the fog away.
In this situation, best avoid using wet wipes, dirty cloths, and especially your hands as these leave nasty streaks on the windshield.
When it dries up, serious stains and streaks can be left over which can interfere with visibility, especially at night.
Use a clean, cotton cloth or even a clean chamios cloth. I would recommend wiping from side to side instead of using a circular motion. Also, make a couple of runs instead of one single swipe.
This way fewer streaks should be left over.
Nevertheless, there will almost certainly be, leftover streaks however careful you are.
Know that you’ll probably have to clean the inner side of the windshield soon after.
In the end, one more important tip on the topic of how to defog a windshield.
If possible, wait and let the windshield and the rest of the windows properly defog before you start driving.
At least wait for the windshield and front windows to defog completely.
I’m saying this as lots of people, mostly because they are in a hurry, let the windshield defog just a bit or not at all and then start driving.
By doing this, your vision of the road is similar to something like looking through a keyhole.
No need to say how dangerous this is for your safety and other participants in traffic. You can’t see almost anything.
If it’s that much of a hurry or an emergency, then at least wipe the windshield with a cloth or your hand and clean the streaks later.
Anything is better than not seeing the road and possibly causing an accident.
Written by: Sibin Spasojevic
Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com
HOW TO DEFOG A CAR WINDSHIELD? YOUTUBE VIDEO