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How to Stop Your Car Windows From Fogging Up Inside


JP993 is a self-confessed car and motorcycle addict, having saved thousands over the years working on and maintaining his vehicles himself.

With the weather getting colder and wetter, the hindrance of getting in our cars first thing in the morning with frozen fogged-up windows is upon us. This isn't great when you're late for work. So what can you do to stop your car windows from fogging up?

First things first, clear the frost on the outside of the windscreen, if any. This will increase the temperature slightly of your screen.

If you do this job with the engine running, great, but I have to emphasize that you should not turn your car's heating on as soon as you start the car. The heat you get from your heaters is drawn from the engine's cooling system. (Confused yet?) If you turn on your fans straight away, you'll be taking away the little heat the car has generated and actually be cooling the engine. Don't turn your heaters on for a good five or ten minutes; after that, you can blast the heaters and clear your screen a lot quicker than if you had them running from startup.

OK, this step may not sort out a steamed windscreen if there's a problem, but it may get you on your way quicker.

If your car steams up no matter what you do, then here are a few things you should do to prevent excess moisture building up and to maybe eliminate some causes of that.

  • If you are always in a hurry and wipe the windscreen on the inside with a mitt or tissue, this could be one of your problems. Doing this makes the windscreen dirty and oily, making it easier for the moisture to build up, so no sooner have you wiped it than it steams up again. Try to avoid wiping your windscreen.
  • Get some good window cleaner, like 5-star rated Invisible Glass Cleaner. Rain-X does a windscreen repellent for the outside which I can not rate high enough; this stuff is excellent. It dramatically increases visibility on those journeys when your windows wiper can't keep up. By cleaning your windows, you should dramatically reduce the moisture buildup.
My favourite windscreen cleaner

My favourite windscreen cleaner

  • If the heaters inside your car never get hot, then your problem may be that your car's thermostat has gone. The job of the thermostat is to stop water circulating around the engine until it reaches a certain temperature, thus making the engine warm up quicker. This is not just a benefit for your heaters, but it lets your car's oil reach its operating temperature quickly. So if your heaters just never get hot, then your car may need a new thermostat. These are very cheap to buy and pretty simple to change; any mobile mechanic should be to change your thermostat in under an hour easily. (To heat your car, you can also buy a 12-volt heater that plugs straight into your car's cigarette lighter socket and gives instant heat.)
  • Also feel your carpets for water or dampness, if you suffer from your car's windows fogging up on rainy days even more than on the usual cold, damp days, Check your footwell carpets. If they are excessively wet, then you may have a problem with your windscreen (a crack or poor seal) or a leak in your heater matrix. You can tell if your heater matrix is leaking because if it is, you will lose water in the header tank. A cracked windscreen can be changed on your insurance if you are full comp.

The best thing to do is clean your windscreen with a good-quality auto window cleaner, like Invisible glass cleaner, and see if this reduces moisture build-up. You will always get fogged-up windows; older cars will suffer more from this problem, due to them having less of everything. If you're having problems with heat, then you need to look more on the mechanical side of things; and if you have water in the car, you'll never get rid of the fogging until you have caught the culprit.

In short, here are seven things you can do remove or reduce fogging up:

  1. Clean all your windows properly on the inside.
  2. Remove frost from your windscreen quickly with a liquid de-icer.
  3. Do not use a sponge or cloth to wipe it off.
  4. Give yourself plenty of time to warm your engine up so your heaters can remove the condensation.
  5. Open your windows slightly, if your clothes are wet, to let the moisture escape. Put wet coats in the back or in the boot, if possible, to put the moisture at the back of the car.
  6. Check your footwells for puddles.
  7. Replace a cracked or chipped windscreen.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


TB674 on March 06, 2019:

Correction I was told the compressor is running not pump as I stated earlier.

TB674 on March 06, 2019:

Hey Eddie is there a way to stop the defost from the beginning. As a diver we use toothpaste and rub it on our mask. I am not sure what negative side affects that would have on seeing out a windshield plus it would require a pretty good bit of toothpaste and a lot of arm work. Rinsing off the excess would be challenging as well. I have no idea what in the toothpaste stops the diving mast from fogging up just that it works.

The real problem I have is neither my AC or heater circulate air in the cabin of my car. I had the freon in the system topped off and have change the fuses. I was told the AC pump is running. So, in my guesstimation I would think there must be a blower to then push the air through the vents and that probably the cause of my problem. I am single mom and we just moved to a new very small NC town and not even sure who would fix this type of issue except of course the dealer who would I believe would be the most expensive place to take my Kia Sportage. Do you have any idea or suggestions for me? This is very dangerous since I can't see out but sometimes don't even realize till I get driving and the are hit with a more well lit area or street lights.

Venus on October 28, 2018:

Hello Eddie. My defrost doesnt work on my car and it does alot of raining and its cold here in Baltimore. I drives a cab at night. Can you help me to remove fog from my windows.

LTD4 on January 22, 2016:

It don't work

hugh on June 21, 2012:

I just get my girlfriend to wipe

thewindows when they fog.

JP993 (author) from England on July 18, 2011:

Not only is it annoying its dangerous too, I hate it.

Karl2294 on July 17, 2011:

This annoys me more than anything on earth, I hate the experience of driving with fogged windows!!

nanolite on January 24, 2011:

I'm going to try this today!

JP993 (author) from England on January 23, 2011:

Sometimes it doesn't matter what setting you have your heaters on the moisture is just too much. which is why you need to look in the usual areas of where you can have leaks or excess moisture built up in your car. Vinegar does work and works well to clean your windows but obviously the odur comes with it. Which is why these cleaning products are recommended.

steve . walker on January 23, 2011:

Guys just set the heating system on fresh - not recirc it works - I live in one of the wettest dampest climates on the planet and my windows are dry and see through nearly all the time - once the heater warms up wooosh no moisture - it works as does cleaning with vinegar and water to keep that film off the inside - for the outside use a good commercial product to keep the road grease to a minimum - have not used this one but sounds good and by the posts it gets a good support too

JP993 (author) from England on January 22, 2011:

Yes opening the windows can be a temporary cure, the problem is, once you shut them again the condesation will reappear if you have moisture inside the car or if your clothes are wet. Also with opening your windows means you will be letting the cold in.

jakevsaustin on January 21, 2011:

opening up windows slightly has helped me

steve . walker on January 21, 2011:

Hi I own 3 cars ranging from 1962 (Chrysler) to 2004 - the best ways to reduce the moisture is to make sure the heating setting is on fresh and NOT recirculate. This will reduce the amount of condensation that builds up in the car as your driving and stays in a vapour form and then comes out again on the windows once the inside of the car cools down. It will also prevent/get rid off the fogged up window effect as you drive.

RJVS from Lancashire, England on January 20, 2011:

Your right the truck is old first registered in 1993. I checked it last night after reading you hub and the seal around the drivers door is not good, as far as the floor goes its plastic lined so doesn't hold damp. Going to sort the seal out to day and i think it might just sort it out. Thanks for the advise!!

JP993 (author) from England on January 19, 2011:

Your welcome RJVS. If its an old pick what's the interior like is there much carpet to it. have you checked if your door seals are good and if theres any rust bubbling around the windscreen?

RJVS from Lancashire, England on January 19, 2011:

Hi JP993 thanks for the info, i have an old Subaru Brat Pick Up truck and its for ever fogged up. It is getting some what annoying but i'll try you rain-x suggestion and hopefully problem solved. Just joined Hub Pages. Already enjoying it and only joined an hour ago.

JP993 (author) from England on November 27, 2010:

Hi Bluehoop,

Rain-X Products are top quality. They're windscreen rain repellent is top top stuff, Its one of those of products that you pick up and think na i'll leave that. But until you try it you be amazed at what it does especially if you drive in heavy rain a lot. Rain-x moved into cleaning products and combined their cleaning products and rain repellent together. I can't rate their stuff highly enough.

I know up north it can be a lot colder than down here but if your getting ice on the inside you have got a lot of moisture inside and felt the carpet in the footwell for dampness? If you keep a matt or towel for a dog in your car then that can hold a lot of moisture too.

Hope my hub helped

Bluehoop on November 26, 2010:

Being the owner of a V reg Citroen Saxo, I completely understand just how bad fogged up windows can get! With it starting to get colder here up north I'm even waking up to find ice on the inside of the windscreen! - Quite irritating if you haven't given yourself enough time to de-ice the car!

I wasn't aware that a water-repellent window cleaner (such as Rain-x that you mention in the post) could actually help, but i guess its certainly worth a try! Thanks for the information!

JP993 (author) from England on October 24, 2010:

You're very Welcome. I try to keep my hubs universal that way everyone can benefit from them. It only takes a small drop in temprature to cause this annoying problem in our cars.

One thing people should also do Is make sure their Anti-Freeze is topped up in their cars coolant. Not only does it help your coolant from freezing but it should also be used in hot countries and all year round as anti-freeze helps reduce under bonnet temps in the summer but it also has anti corresive properties helping the longetivity of your engine ( espcially hot countries ).

Ken Moncrieff on October 24, 2010:

Hi there, the problem you write about is universal and not confined to Blighty. Here in Spain we also have this annoying situation and so do many thousands of others. Nevertheless a useful and informative hub and I for one thank you for it.

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