Why are my car windows misting up and how do I stop it?
Windows mist when damp air meets cold glass, so the fix is nearly always to get moisture out of the car and dry air moving across the screen.
Misted windows happen when warm, damp air inside the car meets cold glass and condenses. Breath, wet coats, damp carpets and rain all add moisture, so the cure is to remove that moisture and blow dry air across the glass.
If your car mists constantly, or the glass will not clear even with the controls set properly, something is adding moisture or stopping the system from drying the air. Here is how to tell which.
What is the quickest way to demist a windscreen?
Set the fan to a good speed, direct the air to the screen, switch on the air conditioning if your car has it, and turn the temperature up. Make sure the recirculation setting is off, because it keeps moist air inside the car. Heated rear screens help at the back.
Opening a window briefly can help clear the worst of it, but the air con method is usually quicker and more thorough because it dries the air as well as warming it.
Why do my windows mist up inside every morning?
Constant misting points to moisture trapped in the car. Wet footwell carpets, a damp boot, perished door seals or rain getting in around the windscreen or sunroof seal are common sources. Blocked drain holes in the doors or sunroof tray can also let water collect.
Check under the mats and in the spare wheel area with your hand. If anything feels wet, find the source before the damp gets worse, because it can also cause musty smells and corrosion.
- Damp carpets or mats
- Worn or damaged door and window seals
- Blocked sunroof or door drains
- Recirculation left on
- Air con not working
Why will my windows not clear even with the fan on?
A weak flow of air is often down to a blocked cabin filter, which is cheap to check and replace on many cars. If airflow is fine but the glass stays hazy, the air con may not be drying the air, perhaps because the compressor is not engaging or the system has lost its charge.
A film that smears across the screen and smells sweet is a different matter. That can be coolant escaping from a heater matrix, and you should not carry on driving as normal if the cooling system is losing fluid.
What can I do myself to stop misting?
Keep the inside of the glass clean, because a dirty film gives moisture something to cling to. Take wet items out of the car, shake off mats, and avoid drying coats on the seats. Switch the air con on briefly in damp weather, even with the heating, and use the fresh air setting rather than recirculation.
If you have a cabin filter, check your handbook for when it is due. A clogged filter restricts airflow and makes everything harder.
What does a garage do and when is it a safety issue?
We would check the controls, airflow, cabin filter and air con operation, look for signs of leaks and see whether the heater and coolant are behaving as they should. The cost depends on whether the cause is a simple filter or a fault that needs dashboard access, so ask for a quote after inspection.
If you cannot clear the windscreen quickly, that is a visibility problem. Do not drive until you can see clearly, and stop if the screen suddenly fogs with a greasy film or if you see steam, or an overheating warning.
Dry air and a dry cabin keep windows clear. If misting returns quickly or the demist feels weak, ask Automaster at Longcombe Cross near Totnes for a quote on checking the system.
Common questions
Why does my car mist up when it rains?
Wet clothes and damp air raise the moisture level inside the car, and cold glass makes it condense. Turning on the air con and avoiding recirculation usually helps.
Is it bad to leave the air con on for demisting?
No. It is a normal use of the system and often the most effective way to clear glass. Many cars do this automatically on the demist setting.
Why does the inside of my windscreen get a sticky film?
Dirt and the vapours from interior plastics build up over time. Cleaning the glass helps, but a greasy, sweet-smelling film should be checked in case coolant is leaking.
Can a faulty seal cause misting?
Yes. A damaged door, boot or screen seal can let rain in, and the damp air then mists the glass. A garage can inspect the area and the drains.
More advice
Ask for a quote
Tell us the make, model, registration and what the car is doing, and we will come back to you. Prefer to talk? Call our quote line on 01803 862152.
Automaster, Longcombe Cross, Longcombe, Totnes TQ9 6PL, United Kingdom