Can A/C Help to Defog My Windshield?

As the temperatures turn cooler in many areas of the country, people are spending more and more time in their cars on icy and snowy streets that, on warmer days, they might have navigated by walking or biking.

Whether you store your car in a garage or park it on the street, you’re sure to encounter one obstacle to operating your vehicle safely: The fogged up windshield, which becomes fogged when the dew point – a combination of humidity and temperature – of a windshield drops below that of the surrounding atmosphere.

Here’s a step-by-step guide to de-fogging that critical piece of auto glass, courtesy of Manpacks.com:

First, try cracking the windows. Because if the air outside is less humid than the air inside your car, then cracking a window will help to decrease the dew point of the interior air, helping to clear the windshield of fog.

Then, crank up the heat through the defrost setting, which will provide higher temperatures to the windshield once your car’s engine has gotten warm. This can also help to reduce condensation or ice on the outside of the glass. Going too hot at first, though, can result in more fogging, so choose a moderate temperature and experiment from there (while the car is not moving, of course).

And, yes, turn on your car’s air conditioner, since that system also serves as a dehumidifier. By turning on the A/C, you will effectively dehumidify the air from your defroster before it is warmed. If possible, turn off the re-circulating feature, as this will help to replace the interior, humid air with less humid air from outside.

Also, try not to wipe the fog from the window with your hands—unless you want to stare through unsightly streak marks later.

Should you run into a situation where you need to de-fog the window quickly, such as when already traveling on the highway, consider opening several windows at once. This will prove a chilly – but effective -- way to replace the car’s inside air quickly.

More questions about air conditioning? Contact AC World today!