How do you fix condensation inside a car?

Condensation inside the car is something that affects all vehicles. We’ve put together a quick primer on what causes car condensation and how to reduce its effects.

What is condensation?

Condensation forms when warm air containing moisture comes into contact with a cold surface, such as your car window. When the warm air meets the cold air, the moisture in that warm air condenses onto that cold surface.

On a car windscreen, this moisture takes the form of hundreds of tiny water droplets that, from a driver’s perspective, looks like a fog.

What causes condensation inside a vehicle?

One or a number of the following things could cause condensation inside the car:

  • Wet clothes/shoes/pets – water on these items will slowly evaporate into the cabin air or, if heavily soaked, cause the seats and carpet to become wet.
  • Breath – when you or your pets breathe, that exhaled air contains a large amount of water vapour which is released into the cabin.
  • A water leak.
  • No circulation of fresh air.

Are new cars more prone to condensation build up?

Modern cars have much better seals, meaning they tend to be more water tight. This means that it’s more difficult for any air inside the vehicle to get out.

If movement is created with a fresh air source, moisture levels will decrease. Well-sealed and insulated newer cars means this movement cannot happen.

Increased insulation also allows modern cars to stay warmer longer after being parked; the longer the air inside the vehicle is warmer than the air outside, the more condensation will appear on the cold windows of the vehicle.

How can I reduce condensation in my car?

As condensation collects in the air inside the cabin, the level of moisture will increase. If this air is not vented to the outside then the condensation problem will increase.

The most efficient way to remove moisture from the air is to use the vehicle’s air conditioning system. This system draws air from the cabin through an evaporator, which causes moisture in the air to condensate in a controlled way and drain out of the vehicle.

If the cabin air is not regularly refreshed then condensation will accumulate, as the moisture-filled air will not be removed. However, you can force this by changing the re-circulation feature from internal to fresh air.

Don’t forget the demister function, either. That’s designed to clear the windscreen of condensation. This works by directing fresh air onto the windscreen, which has the effect of drying the inside of the glass.

If the features of the heater and air conditioning system are used as above, then the amount of condensation inside the vehicle will be reduced. However, it will never be removed – moisture will always be present inside the vehicle.

Believe it or not, one of the key ways to keep condensation at bay is by simply keeping the insides of windows, particularly the windscreen, as clean as possible. A thorough clean of the windscreen will lessen the likelihood of condensation forming, and ensures that any that does form is removed quicker by the demisters.

Check out our official eBay store for useful accessories

You can also buy a car dehumidifier bag. This is a small bean bag full of silicone balls that sits on the top of your dashboard and soaks up moisture from the air inside your car at all times.

53 comments

  1. We bought a Toyota 2008 and as we have gone into the cold weather fund that the windscreen is actually freezing up with ice on the inside. Do you think a seal may need replacing?

    1. Hello Mrs Motala, thank you for your comment.

      It’s difficult to diagnose this without seeing the vehicle in person. If you have tried all of the suggested steps to minimise condensation, it would be worth getting your local Toyota Centre to take a look at things for you.

      Thanks

  2. I have a problem with terrible water droplets of water and condensation on the inside on the front screen, in the mornings. My car is at the local Toyota dealers being investigated and they are also a bit stumped. Perhaps Toyota should investigate this problem themselves as it looks like a common problem.and not to just advise to take it to Uluru local dealer.

    1. Hi Alan,
      Thanks for your comment. We’re sorry to hear this.
      As mentioned in the blog post above, there are better seals on modern cars, making them more water tight and consequently more difficult for air inside to get out.
      This sealing and insulation on newer cars means that movement of air cannot take place, meaning that moisture levels increase.
      There are steps listed in the blog post above that can help with minimising condensation.
      If your Toyota Centre are experiencing an issue in diagnosing your vehicle, they can contact our technical team for further help.
      Thanks.

      1. Thanks for that. It’s been in the garage for two weeks and still no resolution. Probably put to one side and just spend a bit of time here and there on it. Although they did a safety inspection and informed me that the rear trailing arms are worn and they have replaced them, but not the fault it went in the garage for. Further more we bought this car 14 months ago, December 2019 and it was supposed to be inspected. As we have been in lockdown, around last March it had a discharge fault and after a month, yes a month without this car they found it was the interior light. As I said we have had this car 14 months, been in lockdown and the car has not even done 3000 miles in that period. Do you find it strange that trailing arm bushes wear out in 3000 miles or the vehicle was not inspected correctly. Just to let you know I am an ex motor mechanic. Bushes do not determinate in 14 months. I will tell you one thing we will never buy another Toyota. And my last job was working at the Toyota VRC, Portbury

      2. Hi Alan,
        Thanks for your reply. We’re really sorry to hear that you are unhappy with your vehicle and the service received.
        We have emailed you to gather extra details regarding your situation, and we will put you in touch with our Customer Relations team to explore this further.
        Thanks.

  3. I have just bought an Auris estate and a bit disappointed it comes with a thin cover in the boot. Do you have a boot shelf that is a bit more substantial and give a more level floor. Everything else on the car is great.

  4. I have brought a brand new aygo in got it delivered on 27 October 2020 cost £13800 I DID NOT EXPECT THIS CONDENSATION PROBLEM the condensation is so bad I could not see fully nearly knocked a cyclist at a round about
    I demist front windscreen it’s gets cleared in the morning after waiting nearly 8 min and after I have parked and been to shops come back I have got to demist yet again I don’t see anyone else do this they get in their car and drive off like I use to do and it takes over 6 min and it’s still not fully clear it still bad all around the windscreen, it just untold stress and gives me anxiety you say about new cars and air tight BUT how can that be when the car parks are full of new and old cars yet when I look around at all the other cars there is NOT one car with the same problem as mine I have had 5 cars in the past and not one has been like this I have asked family friends they do not have this problem I have also googled that a problem did exist with the older style models but surely you have sorted this out with this new model or are you buying cheap sealants / parts to save money . This car is DANGEROUS I was on the motorway and is started to mist I put the A/C on and demist It was NOT ON recirculate then and the whole front windscreen covered in mist condensation and I mean the whole windscreen I could not see a single thing I had to slow down 20 mph and this car could have killed me and others nearly killed a cyclist at a roundabout due to the mist building up as mentioned above as the sides also build up with condensation
    Took my son to uni we could not even talk as the condensation and mist was so bad and was still building up around the windscreen edges I have photos and videos of this and may other times this has happened it seems to happen a lot when it’s raining or been raining so there must be a leak or the seals are rubbish . The car I would not even give it one star due to this problem
    I have been without a car for a week now as it’s in Toyota and they are still looking at it . Never ever have I wasted so much money I have never ever been without a car it’s a total joke . I would NEVER EVER recommend this car to anyone and in fact I feel I will have write to Martin Lewis and warn others and stand outside Toyota with a big sign to warn anyone buying this car how dangerous this car is and the problems it has

    1. Hi Julie,

      Sorry to hear about this. It sounds like your Toyota centre is dealing with this, but if you are unhappy with their service, we’d recommend contacting the customer relations team here: https://fal.cn/3dFkG

      Thanks

      1. Been in the garage over a week now they still can’t find anything I need my car the problem is not going to go away I will have to borrow the money to buy it outright and I can’t wait to get rid of it and sell it on and the new buyer most likely put a post on here and for you to tell them the same answers you tell everyone else not good enough when there is a fault you know about yet can’t admit to say

      2. Hi Julie,
        Thanks for your reply. We’re really sorry to hear this.
        Our Customer Relations team are best placed to explore your situation with you in further detail, and they can be contacted here: https://fal.cn/3dFkG
        Thanks.

  5. I have a new Rav since 2019. Whenever the temperature hits 0 and below, it’s fogging on the inside of the windscreen plus all windows! I use the air-con at 19C whenever it’s cold, and must use a jacket since i wouldn’t dare put the temperature too high! Hub drives a Merc & his windscreen never fogged out! What am i doing wrong?

    1. Hi Flora, we’re sorry to hear that.

      Please get in touch with your local Toyota Centre so they can take a look at this for you.

      Thanks

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