How do you fix condensation inside a car?

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 on to 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 is more difficult for any moist air trapped inside the vehicle to escape. If movement is created with a fresh air source, moisture levels will decrease.

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.

Fix condensation inside a car

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-rich 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. It’s designed to quickly clear the windscreen of condensation and works by blowing air directly over the surface, 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. Thorough cleaning of the glass will lessen the likelihood of condensation forming, and ensures that any that does form is efficiently dried 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.

Read more: Toyota tyre pressure and size guide

82 comments

  1. I’m having issues with my Toyota CHR. I’ve had the vehicle since March and since the weather has been cold I’ve now started using the AC/heating in the vehicle. Since using there is a bad smell of mould/damp that blasts from the fans into the front of the vehicle where the passenger and driver sit. It’s been at Toyota and they blasted the AC system and it’s not solved the problem. I’ve also noticed before I even get into the vehicle all the windows are misted up and the back window where the boot is, doesn’t demist at all. I can turn the vehicle off, go into a shop for 10 minutes and return to the vehicle being misted up again. I’m unable to use the AC/heaters due to the bad smell and I’m worried about what I might be breathing in. Toyota aren’t too sure of the issue and have mentioned they could re-gas the system but realistically, I don’t think this is going to work and the issues seems to be a lot deeper.

    1. Hi Chelsea,
      Thanks for your comment.
      May you please confirm when and which Toyota Centre you took your vehicle to?
      Thanks.

      1. Hi Pete,
        We are sorry to hear of this.
        Is there anything we can do to assist you at this time?
        Thanks.

    2. Since the AC/ventilation system is so hard to reach, you should try spraying an anti-mold/anti-bacterial product like Lysol into the vents, with the AC on, to suck it into the system. This should do the trick. I’ve used it on AC window units in the house, since mold and bacteria build up on the drain pan sometimes. Some places sell implements for cleaning (long wire brushes), but I think that might be risky. You could damage the interior. In future, try leaving your windows open on dry days and make sure to close them (and the sunroof) in damp or rainy weather. Also, get one of those car dehumidifiers (a bag of silicone), to keep the inside dry all the time. Good luck!

  2. I’m having the same problem with my chr I have the air con on the air circulation inside is off the window is open slightly I started the car up waited 5 min before I got in with the front window fan on full I managed to get a small gap at the bottom clear to see although I shouldn’t have driven with a steamed up screen I had to to get to work I traveled 3 miles and still the screen is still all fogged up this is the worst car I have ever had for this issue it must be a fault with these cars I shouldn’t have condensation inside the car running down the inside the screen

    1. Hi Heather,
      We apologise for the inconvenience this has caused.
      We would recommend taking your vehicle to your nearest Toyota Centre so investigate this further.
      Thanks.

      1. We have the same problem
        My husband starts work early and has to sit in a damp car with water running down the screen not right
        Car only 10 months old

    2. Did you manage to get this fixed? I found this page by searching condensation in cars…. I have this exact same problem. Car is misted up in cold weather, takes ages to clear and mists up again if I get out and then start it up a short while later. Garage has checked and there are no leaks anywhere. Evaporator was replaced last summer so assuming that isn’t the problem. (Air con doesn’t smell). At end of my tether with it all.

    3. I had this problem for months especially saturation in the boot of the car took a few days to dry. Until I changed the inside recirculated air mode knob/lever to outside air mode knob/lever
      Problem solved no more pools of condensation

      DRIVERS USERS GUIDE
      Switching between Outside Air and Recirculated Air Modes
      turn the INSIDE recirculated knob/lever mode (diagram car bonnet closed) to OUTSIDE recirculated air mode (diagram car bonnet opened)

  3. I returned to my brand new CHR (1k on the clock) after being on a 12 day cruise and the windscreen was covered in condensation, running down the inside like rain? Think there must be a bigger issue at fault?

    1. Hi John, thanks for your comment.

      We’re sorry to hear that you are experiencing high levels of condensation in your C-HR. This is not an issue that we are aware of. If the tips listed in this article are not helping, we would recommend getting in touch with your local Toyota Centre to allow the team to review this in person.

      Thanks.

  4. Hi,the front camera of my 2016 toyota avensis is constantly blocked with condensation turning off all of the sensors for the saftey sense system.Even having the climate control on full power cannot get into the enclosed area of the windscreen to demist it.Can you advise please? Thank you

    1. Hi Enda,
      Thanks for your comment.
      We would recommend taking your vehicle to your nearest Toyota Centre so they can physically inspect it for you.
      Thanks.

  5. Dear,
    I’m Ahmed, I finance a zero mileage toyota car, reg no HF18RSV.
    After 3-years 10-months later, car auto gearbox not working, when I buy car, I was believed toyota is a well established company. And only run my car 130,000 mileage.and all time service my car with main dealer, I’m very disappointed that dealer said it’s not cover warranty. Thanks

  6. Hi all

    I have a 2008 Hiliux D-4D and I have a condensation issue also, there are no leaks in the foot wells. i’ve checked out the AC and heater coils and no problem there, checked the condensate drain, I even get ice on the inside in the winter! There is a damp/ musty smell when you turn on the ventilation fan as if there are water droplets on the AC/ heater matrix fins? Some times there are water droplets running down the inside of the screen. The condensation issue is particularly bad when there is a big temperature drop i.e when its really cold.

    1. Hi Ian,
      We would recommend taking your vehicle to your nearest Toyota Centre so this can be physically inspected.
      Thanks.

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