What To Do When Your Windshield Fogs Up

It’s a cold morning, you open your car door, sit start the car and immediately notice the windshield fogging up. What now?

Everyone has had to deal with a foggy windshield at one point or another, and everyone seems to have their own way of fixing it.

Some might use a small, portable squeegee,  others a dry cloth. Some use the car heater, other’s use the A/C. And then some people just fiddle with the controls to no avail, not realizing that the condensation is actually on the outside of the windshield! So what should you do?

Why Windshields Fog Up

To find the best solution, let’s take a closer look at the problem – fogging. Windshield fogging is caused by water vapor condensing on the inner surface of the glass on a windscreen. It can happen one of two ways.

  1. The first way begins with air that gets trapped inside a car from the previous day. This previous day air is more humid than the current cold outside air. Warmer air is able to hold more moisture than cold air, in fact it can hold up to double the amount of moisture! When the more humid air inside the car comes in contact with the cold windshield glass it releases some of its moisture, leaving condensation or fog on the glass.
  2. The other way is caused by us. When we sit down in a cold car, we inhale cool air and exhale air that is warm and humid. As a result, every breath we take puts more humidity in the inside of the car, which condenses on the glass and fogs up the windscreen.

How To Fix A Foggy Windshield

Fog can be cleared many ways. While there is no master solution that works the best every time, there are two common strategies that are likely to work really well.

Dry Out The Air

Depending on your comfort levels, the better option could be to run the A/C. We recommend using this method when temperatures outside are above freezing and the fog is caused by wet, damp humans inside the car. Running the A/C on cold is best, but you can turn the dial to a warmer temperature while still running the air-con and still get good results.

Evaporate The Water Vapor

For a usually quick and easy fix, run heat through your defrosters and it will cause the condensation to evaporate sort of like how a clothes dryer uses heat to evaporate moisture. This method usually works well when you catch the fog building up early on and when the temperatures are cold.

For extremely foggy windshields, you can use a dry cloth or small squeegee to quickly clear the fog and then run the air-con on cold. If running the air-con on cold makes you too chilly, then slowly increase the temperature until the air dries out inside your car. Remember when trying to dry up the air inside your car to bring outside air in instead of circulating inside air. Most cars nowadays do this automatically when the defrosters are on.

If you have other methods that work well for you, please share in the comments below! We always look forward to hearing from you here at Deco Windshield Repair.

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