How to Stop Condensation on Car Windows: 10 Useful Tips

Condensation on car windows can’t only be damaging to the interior but can also be a danger when driving. There is a higher chance of an accident happening when the windows fog, limiting visibility, and steps should be taken to reduce this factor when driving.

To stop condensation on car windows, you must reduce the amount of moisture inside the car. This means checking for any leaks around the doors and windows, airing out the car whenever possible, and running the heater to dry damp seats. Close the windows on rainy days, and remove trash right away.

This article will determine the cause of condensation on car windows and how you can prevent it from occurring in the future.

Condensation that is occurring on car windows.

What Causes Condensation on the Inside of Car Windows

Condensation is caused by warm, humid air coming into contact with a cold surface. It may present as foggy windows or as dripping water down the glass surface of the windows. It can also be seen on the side of a cold drink on a hot day.

As the cold liquid cools the cup down, the warm air around will come into contact with the surface of the glass or plastic and create condensation. This often makes the outside of the cup wet, which can pool on the table.

In a car, this is typically caused by body heat and breath warming up the air in a cold car. As the warmer air touches the cold windows, it can cause them to fog up and create condensation. Another cause can be wet clothing or seats. As the car warms up, this moisture is released into the air until it makes contact with the still cold glass.

Condensation is more of an issue in colder months, as the temperatures outside the car keep the window cold, even as the heater works to warm the inside of a vehicle.

However, it is also common in humid climates, as the air conditioning begins to work. As the air inside the car starts to cool and the windshield’s inner surface cools, any moist air that comes into contact with the glass will cause fogging and condensation.

Some common causes of foggy windows include:

  • Wet or damp clothes, shoes, towels, etc.
  • Human breath
  • Damp carpets, typically on a rainy day
  • Leaks from the sunroof, doors, or windows
  • Issue within the ventilation system
  • Hot food or beverages that are visibly steaming
  • Coolant leaks from within the heater
  • Leftover trash and food wrappers

Since our breath is not the only cause of condensation, it is essential to check the vehicle for signs of dampness and possible leaks. In addition, removing any damp clothing, towels, or shoes will help reduce the chances of warm moisture entering the air.

Similarly, clean the car of leftover food, drinks, and wrappers that may have food or drink remnants. Though small, these can create moisture if the car warms enough, especially if they are in plastic receptacles.

Some simple changes you can make include:

  • Park in a garage if possible to keep the car out of harsher temperatures.
  • Avoid using car covers, which will prevent fresh air from circulating in the car.
  • Check that the windscreen washer pipe is intact, as a leak can find its way into the interior.
  • Keep the windshield clean to prevent dust or dirt, which will attract moisture.

How to Stop Condensation on Car Windows

Check for Signs of General Dampness

Check under the mats in the front, back, and trunk, and feel along the doors’ base and edges for any signs of dampness. This could be a sign of a damaged seal or leak in the car.

Wetness can often be found in the trunk, under, or around the spare tire. This usually comes from a damaged seal and collects in the lowest part of the trunk. Repair any broken seals to prevent further water from leaking into the car.

Leave a Window Ajar

On warm, humid days, leave a window slightly ajar to help aid in air circulation. This will help keep the car cooler, and the fresh air will help keep it dry by circulating the moisture out of the car.

However, it is important to remember to close all of the windows at night to avoid moisture finding its way in. Water will evaporate from the ground on warmer days and find its way into the air as water vapor.

When the evening starts to cool, and this water vapor comes into contact with the still-warm ground, it will condense back into a liquid. Known as dew, this is often seen in the early morning and evenings.

Ensure Windows Are Closed in the Rain

Any moisture that finds its way into the car can lead to foggy windows and condensation on car windows. To stop this, it is crucial to keep the car as dry as possible. On rainy days, ensure the windows and sunroof are fully closed and sealed, preventing excess water from entering the vehicle.

Don’t Use the Recirculating Air Function

Typically depicted as an arrow circling on itself inside a car, the recirculation button is used to aid the air conditioning in keeping your car cold.

As the air conditioning works, it will draw in air from the outside, working to cool it before releasing it into the warm car interior. Using the recirculation button prevents the car from pulling in hot air and recirculates the already cold air, keeping the car as cold as possible.

However, in the case of foggy windows, this is not beneficial. By recirculating the air already inside the car, this function will continue to cycle through any moisture in the air, not allowing it to escape. To stop condensation, the system needs to pull in dry air from the outside.

Use the Air Conditioning

Though it may seem counterproductive and wasteful to run the air conditioning on a cold day, using the air conditioning will help to remove moisture from the air. Turn it on once the car is at a comfortable temperature to help keep the car dry.

Also, the system should be run at least twice a month, even in the winter, to prevent the pipes from drying out and cracking, which will cause leaks.

You might also want to read: How To Clean The AC Filter In Your Car

Keep Damp Clothes Out of the Car

Damp clothes can mean wet shoes, towels, or coats from the rain. These will cause condensation inside the car as they release their moisture into the air. Mixed with your body heat, you will see condensation much faster in such situations.

Keep any damp clothes in the trunk if they must come into the car, and always remove them immediately or as soon as possible. To prevent them from seeping moisture into the car’s fabric, protect the seats and carpets with a layer of plastic.

Keep the Seats and Carpets Dry

On a rainy day, it is impossible to keep water out of the car. It will be on your shoes, pants, and coats. This will then make its way into the seats and carpet, soaking in as you sit. The next time you enter the car, this moisture will likely still be present and cause condensation even on a dry day.

To dry the carpet and seats, run the car’s heater and leave the windows open slightly. The warm air will dry out the moisture in the fabric, and the water vapor will make its way out through the open windows.

Remove Trash

Trash, such as used coffee cups and food wrappers, will likely still hold some food or drink. This will also retain moisture, and though it may not be a lot, it will add to the humidity in the air. From empty water bottles to the remnants of a morning coffee, there will be some liquid left in the receptacle that will evaporate on warmer days until it reaches the cooler window, creating moisture.

Always remove leftovers and empty drinks from the car, and keep trash in plastic bags until it can be thrown away properly.

Check the Heater Matrix

The heater matrix can be found inside the dash. This small radiator allows warm coolant to run through from the engine, which warms the air that blows through the vents. A leak from this area will drip down and pool on the carpets in the footwell.

If there are constant damp spots on the carpet by the driver and passenger footwells, even on dry days, the heater matrix will need to be checked. If you’re not confident in removing the dash, the car will need to be seen by a professional, and the matrix will need to be fixed.

Check the Windows and Sunroof for Debris

Debris such as fallen leaves and general dirt can prevent your windows and sunroof from closing correctly, which means the seal is not secure. In this case, moisture and water from outside will seep in through the open seal and collect inside the car, especially with a sunroof.

Open the windows and sunroof and thoroughly clean the seals, removing anything that may have collected. When not in use, keep the shutter closed over the sunroof if there is one.

Conclusion

Condensation is caused by water vapor in the air coming into contact with a cold window. The moisture can come from human breath and body heat, along with any dampness in the car, from wet seats to wet clothes and shoes.

You can prevent condensation on car windows by working to keep the car dry. This can be done by running the heater with the windows open to dry any wet areas, removing wet clothes or towels as soon as possible, and running the air conditioning, even in the winter, to encourage the circulation of dry air.

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