You get into the car on a cold morning, start the engine, and within a minute the windscreen has gone completely white. It’s annoying when you’re already running late, and it’s not safe to set off until you can see properly.
Foggy windscreens are really common at this time of year, and there’s usually a simple reason behind it.
Why your windscreen fogs up
Warm air holds a lot more moisture than cold air. Every time you breathe out, you’re adding moisture to the inside of the car. Add a damp coat, a wet umbrella or muddy boots and there’s even more of it. When all that warm, damp air meets cold glass, it turns into tiny droplets of water on the surface. That’s the fog you see.
Autumn is the worst time for it. The mornings are colder, the weather is wetter, and the inside of the car never quite gets the chance to dry out.
How to clear it quickly
If you’re stuck with a fogged up windscreen right now, this is the fastest way to deal with it:
- Turn the heater up and point the vents at the windscreen
- Switch your air con on. It dries the air before it hits the glass, which is why it works so well, even in winter
- Turn off the recirculation button so the car brings in fresh air from outside
- Crack a window open for a minute if it’s really stubborn
Try not to wipe the inside of the glass with your hand or sleeve. It tends to leave greasy smears that make the problem worse once the fog returns.
How to stop it coming back
A bit of prevention makes a big difference.
Clean the inside of your windscreen properly. A film of dust and grime gives moisture something to cling to, so a dirty windscreen fogs up much faster than a clean one. Use a proper glass cleaner and a clean microfibre cloth.
Try to keep the inside of the car as dry as you can. Take wet coats, umbrellas and towels out of the car rather than leaving them on the back seat, and shake off wet shoes before you get in. If your footwell mats are damp, take them out and dry them off.
It’s also worth knowing that a blocked cabin filter can reduce the airflow through your vents, which makes it harder for the car to clear the glass. If the air coming out seems weaker than it used to be, the filter is worth checking.
When it’s more than just condensation
Sometimes a foggy windscreen is a sign of something else going on. Keep an eye out for any of these:
- The windscreen fogs up constantly, even on mild days
- Your carpets or footwells feel damp
- There’s a musty smell inside the car
- A sweet smell from the vents, or an oily film building up on the inside of the glass
Damp carpets and a musty smell can point to a leak, perhaps from a worn door seal or a blocked drain. A sweet smell and a greasy film on the glass can mean coolant is leaking from the heater system, which needs looking at straight away.
If your air con isn’t clearing the glass the way it used to, it may also be low on gas. We covered that in our air con blog, and a regas is a quick job that we can usually do whilst you wait.
Get it looked at
If your windscreen keeps fogging up and you can’t work out why, bring it in and we’ll take a look. Give us a call on 01604 589179 for free, friendly advice, or pop in and speak to the team.
