In cold weather, you may notice your windows fogging up. Then you can’t see where you’re going, and suddenly you and those around you are in danger. So, what causes your windows to fog up in cold weather, and how can you stop 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, of course. Blower motors must work, and the air conditioner condenser and its other components need to be in good operating condition. Plus, you have to be able to roll down your windows.
This is why it’s 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? Add to that the fact that, in many vehicles, the air conditioner automatically comes on when you turn on your windshield defroster. That way, the A/C removes moisture as the heat warms the glass to prevent condensation, a very effective one-two punch. It’s a good idea to have your NAPA AutoCare Center perform an A/C inspection every year to make sure it’s working as it should all year round.
Oh, one thing that helps prevent fogging is making sure the insides of your windows are cleaned regularly. Dirt and oil on the glass give water molecules something to cling to. Boy, this sure clears up the subject of foggy windows!