High humudity in the car


I own a 1999 Honda Civic hatchback. I live in Oregon, where it rains quite a lot.

I’ve noticed that there is a fair amount of humidity in the car, to the point that mold is developing on the dashboard. I don’t drive very often, and there’s water on all windows when I get in the car.

My question is how can I limit or manage the humidity level in the car. When I drive I blow very hot air and open the windows, but this is a temporary solution.

Any suggestions are greatly appreciated.



I installed these on two of my vehicles.


The Ventvisors let me keep the windows cracked an inch or two for ventilation.

Ed B.

I think you should consider the possibility that there is a leak somewhere, and water is getting into the car. Check under the carpet and see if there’s water soaked into the padding anywhere. How about the spare tire well? A clogged AC drain tube will allow water to drip onto the front floor. Clogged sunroof drains can be a problem, too.

Run the AC along with the heat when you drive. The de-humidified air from the AC will help dry the car, but I don’t think that will be enough. You have to figure out how the water is getting in.

If you have AC make sure that button is pressed also when drive about with very hot air and windows open.

A surprising number of people operate their cars with the HVAC system set to recirculate the air, rather than drawing in outside air. Are you sure that you have the HVAC system set properly, so that outside air is drawn into the car?

Also make sure your heater is not in the recirculation mode; you need to bring fresh air into the car.

In addition to all the excellent advice above, you may need to drive off the moisture.

Whenever you can park in the sun and safely open the windows, do so, even if only part way.

If you can place a small electric heater and/or fan in the car and run them with the windows open, that will make a big diff. It may take several days.

Remove any pads that are covering the carpets. You need to evaporate the water that is in the carpet, its underpadding, the seat fabric and foam, etc. Remember the trunk - it may need to be treated, too.

Thanks all for you advice.

It seems that I have a bad seal somewhere, as there is indeed water in the trunk. After talking to a mechanic, it appears that fixing it will cost a lot, so I might drill a hole in there.

I guess all I can do now is to air and heat it up, as suggested.

Thanks again.