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. I have a pergoet 107 which was recalled for the side window seals. I have just noticed the back seat is wet and the boot.
    Shall I take it back to garage

  2. I’m picking up a Corolla this Thursday 30th Jan. Am changing from a Vitra so I’m hopping the car is as good as they say.

    1. Hi Gordon,

      Thanks for getting in touch. Congratulations on the new car! We’re sure you’ll enjoy it. When you’ve picked it up, feel free to share pictures of it with us on our social channels.

      Thanks.

      1. I have Toyota Prius plus 2013, I recently replaced rear windscreen and spoiler due to accident damage. when I collect from garage I took the car straight to hand car wash, they did full valet cleaning as it was very dirty even they washed carpet and mats. I noticed condensation and frost all window glasses. any recommendation to get rid these problems.

  3. Hi Nur,

    Thanks for getting in touch. It would seem that after having the car cleaned there may still be a lot of moisture left behind, potentially from the carpet and mats. This leftover moisture can then cause condensation, which in the current weather, can then freeze.

    As mentioned in the blog post above, to help with condensation we would recommend making use of the vehicle’s air conditioning system to keep the cabin air regularly refreshed, keeping the insides of windows, particularly the windscreen, as clean as possible and potentially buying a car dehumidifier bag.

    You can find out more details in the blog post above.

    Thanks.

  4. Toyota cars are the worst for this, mine has that much water inside it needs a squidgy to clean it. My partner has a Nissan and never has the same issue. My best mate has a Ford and worth 1 click of the button his windscreen is demisted in seconds.

    All new toyotas should have a heated windscreen option has started. Its embarrassing when even with a bit of frost which has caused the INSIDE of the window to freeze it takes my car 10 minutes to defrost and Demist

    1. Hi Keith,

      Thanks for getting in touch. To help with condensation we would recommend making use of the vehicle’s air conditioning system to keep the cabin air regularly refreshed, keeping the insides of windows, particularly the windscreen, as clean as possible and potentially buying a car dehumidifier bag. You can find out more details in the blog post above.

      If you feel there is an excess amount of water inside your car, we would recommend visiting your nearest Toyota centre as they are best placed to assess the car in person and make any necessary recommendations. You can find your nearest dealer here: https://www.toyota.co.uk/forms/forms?tab=pane-dealer

      Thanks.

  5. 2010 Prius has condensation behind the dashboard glass (on the right side, not the reflected speedomoter display). Makes it very difficult if not impossible to read the display. Have been running the A/C on high lately due to temp here in Phoenix. Wondering if condenstation will go away, or any tips on how to reduce or prevent based upon A/C settings?

    1. Hi Frank,

      Thanks for getting in touch. We’re sorry to hear about the issue you’re experiencing. We would recommend contacting Toyota in your region for further help with this.

      Thanks.

  6. I have this issue with my brand new $80,000 hilux RX – I find it ridiculous that Toyota recommends buying a car dehumidifier bag… apart from not being able to see the road the car is perfect 👌

  7. Hi,

    Just thought I would ask this question on here. I have a 2018 Toyota Auris Hybrid and have owned it since October 2020. I noticed on my drivers and passenger windows that there was rain and mist on the outside of the glass so I put the windows down to clear this but the wiper seals that are fitted to the doors didn’t clear the glass.

    Is this normal or do I have a problem with the door wiper seals? All other cars that I have owned in the past always wipe the windows when they are opened or closed.

    Thanks

    Tim

  8. I have a 2017 Yaris and the condensation is far worse than my old 2002 Corsa.?
    I’d expect it on any old car, but not a 3 year old car. Seals all appear OK.?

    1. Hello Paul, we’re sorry to hear that.

      Please get in touch with your local Toyota Centre to allow the team there to take a look at your Yaris in person.

      Thanks

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