My 2003 Opel Agila always seems to steam up constantly while driving, in all weathers. I do not have a damp problem in the car either, everywhere seems dry.

I have checked the following things:

  • Air selector is not on recirculate mode
  • Heating works, and the fan is fine (seems to run okay, good airflow)

I don't have AC so I can't leave this running to dehumidify the air.

I have even bought a 12v dehumidifier to try and solve the problem, but this doesn't seem to work that well.

I always have to drive with the heater on full, which makes the car unbearably hot, or drive with the window wide open, which makes the car very cold.

Is there anything I can do to stop my windows misting up while driving?

  • 1
    Is the car losing coolant at all? A pin-hole in the heater core could cause excess moisture in the cabin.
    – JPhi1618
    Commented Nov 16, 2015 at 21:31
  • I am with @JPhi1618 on this. Whenever I have experienced extreme misting, it has either been water ingress, or a leaking heater matrix.
    – HandyHowie
    Commented Nov 16, 2015 at 22:28
  • To me, this sounds like recirculate mode. Are you sure the mechanism is working? (do you notice smells from outside?)
    – sweber
    Commented Nov 16, 2015 at 22:36
  • @sweber How do I check for recirculate mode problems?
    – George
    Commented Nov 17, 2015 at 7:37
  • @jphi1618, I'll top up the coolant and check
    – George
    Commented Nov 17, 2015 at 7:38

1 Answer 1


Try just driving with a window open a crack to allow the inside to breath a little bit. It's your breath which usually causes the windshield to mist up.

Also, use a product like Rain-X Anti-Fog. By ensuring your windshield is first clean and then by applying the product, there is nothing for the humidity to stick to, so no fog.

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