The Foggiest Idea

In cold weather, you may notice your windows fogging up. You can't see where you're going, and suddenly you and those around you are in danger. You may wonder what causes your windows to fog up in cold weather, and how to avoid it?

Fog is simply moisture condensing on a cold surface. When the air inside your vehicle is moist and warmer than the outside air, it hits the glass that's cooled by the outside temperature, and you get fog.

If your windows fog up, you probably already know to try the defroster for your windshield. You may also have an electric defroster for your rear window and outside rearview mirrors. Electric elements in the window and mirror glass heat up, so the moisture doesn't condense on the glass. If the defroster isn't working on all the windows, turn up the temperature setting on your heater. Hot air holds more moisture. Switch on the air conditioning. As the air moves over the cooling coils, the moisture is removed. Turn your ventilation system off the "recirculating" setting, so it lets in outside air. Open a couple of windows slightly to move some of the moist, warm air out as the cooler, dry air comes in. Your windows should quickly clear up. For this to work, all the systems in your vehicle must be working properly. Blower motors must work, and the air conditioner condenser and its other components need to be in good operating condition. You also have to be able to roll down your windows.

It is essential to keep all of the components in your vehicle in good working order. Who knew it was so important for your air conditioner to work in cold weather months? In many vehicles, the air conditioner automatically comes on when you turn on your windshield defroster. The A/C removes moisture as the heat warms the glass to prevent condensation. It's a good idea to have an A/C inspection every year to make sure it's working as it should all year round.

If you find yourself in a situation where you can’t stop the fog and it’s impacting your ability to see through your windshield or windows, use a towel. It’s a great idea to keep a towel in your dashboard compartment or trunk for instances just like this. Before you drive away, or if you need to pull over, grab the towel and thoroughly dry your windows inside and out. Make sure to turn on the heat or A/C as you do this, so you dry out the air inside your car as well. 

Making sure the insides of your windows are cleaned regularly can reduce fog as well. Ever notice how your windows seem to fog more after the first big fog? That’s because the condensation/fog leaves a residue that makes it easier for moisture to attach next time. To prevent this, clean windows regularly. Window cleaning products work well, or you can buy car-specific products. Use a lint-free rag and clean both inside and outside your windows. Let them fully dry before you roll them down, but leave doors cracked so you don’t have chemical fumes seeping into your car seats. 

Boy, this sure clears up the subject of foggy windows!

Eureka Brake & Automotive <br/>707.443-2122 <br/>

Revised from content contributed by NAPA Service Assistant