Car Windows Keep Fogging Up? 6 Mistakes That Make Your Defroster Less Effective, by Tony’s Garage Guide on YouTube. 14 min 13 s.
- Video length
- 14 min 13 s
- Time to do it
- 5 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Turn off air recirculation and switch the system to fresh outside air. Recirculation traps the moist air you breathe out inside the cabin, so the glass fogs again within minutes.
Switch the A/C on even when you want heat. The air conditioning removes moisture from the air, which is the main job when defogging.
Set the airflow to the windshield defrost symbol and raise the fan speed. Direct the side vents toward the front side windows too.
Set the temperature to warm once the glass starts to clear. Warm dry air holds more moisture and keeps the windshield clear longer.
Check whether the fog is inside or outside. If it sits on the outside, run the wipers or adjust the vent temperature instead of blasting the defroster.
Dry out the cabin. Shake off wet coats and mats, and leave a window slightly open for a few minutes on damp days to let trapped moisture escape.
Replace a clogged cabin air filter and check that the heater blows hot. Weak airflow or a cold heater often means a maintenance problem, not a settings problem.
Use the max defrost button for a fast clear, then drop back to normal settings once the glass is clear. Keep the A/C on to stop the fog returning.
Tips and common mistakes
Never wipe the inside of the windshield with your hand, since skin oils smear and make fogging worse.
Clean the inside glass with a proper glass cleaner every few weeks, as a dirty film holds moisture.
On cold mornings, start the engine and let it warm briefly before driving off with the defroster on.
If the windows keep fogging after these steps, check for a leaking heater core or water getting into the cabin.
Questions
Should I use hot or cold air to defog the windshield?
Start with warm air and the A/C on. Warm dry air clears fog faster and keeps the glass clear, while cold air mainly helps on hot, humid days.
Why does my car fog up even with the defroster on?
Recirculation is usually left on, or the A/C is switched off. A clogged cabin air filter or damp interior can also keep moisture trapped inside.
Does rain or damp weather make fogging worse?
Yes. Wet clothes, mats and shoes add moisture to the cabin, so dry them out and crack a window open briefly to let the humid air escape.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
