4 Things That Can Cause Frost On The Inside Of Your Windshield & What To Do About Them

Posted on: 22 October 2015


If your winter mornings are delayed by frost on the inside of your windshield, you may be wondering what could be causing the problem. Frost can accumulate on the inside of your windshield for a number of reasons. Frost is just frozen condensation, which is caused by too much moisture inside your vehicle. So where does the moisture come from? Here's what can be causing the problem and how to fix it. 

Wet Carpet 

If you trudge through snow to get to your vehicle, your shoes or boots may get covered with snow. When you turn the heater on, the snow melts from your shoes or boots and gets right into the carpet. This moisture will get trapped in your vehicle if the carpets do not dry out before the end of the day.

Remove as much snow as possible from your shoes and clothing before you get into your vehicle. You can also leave your windows slightly open to allow moisture to escape during the night so it doesn't condensate on your windshield and cause it to frost over. If you don't want to leave your windows open, you can place an absorbent material in your vehicle, such as a cup of baking soda or a few pieces of chalk. 

Windshield Leak

If the rubber sealant around your windshield is damaged, it can cause water and moisture to seep into your vehicle. Rubber seals can disintegrate over time, which can cause problems with leaks and with the integrity of your windshield. If this is your problem, you may also hear road noise or the sound of whistling air when air gets through the cracks in the seal when you drive.

Douse your windshield with water and then inspect the edges of the windshield on the inside to look for water droplets, or ask a windshield repair service to inspect your windshield sealant for signs of deterioration. If cracks are found, then you'll need to have the rubber seal replaced by the repair service. You can visit sites like http://www.centralglassutah.com to learn more about windshield repairs that might be necessary. 

Heater Core Leak.

The heater core is usually located underneath or behind the dashboard. It is what is used to heat the interior of your vehicle. The heater core uses coolant from your radiator. Leaks from the heater core can cause moisture inside your vehicle. If this is the problem, you will smell a sweet, syrupy odor from the coolant. You might also find that the frost and condensation has a slimy residue.

Another sign that this is your problem is if your coolant levels are low on a continuing basis. If this is your problem, you'll need to have a mechanic check over your vehicle as soon as possible. A coolant leak can cause your vehicle to overheat which, of course, can cause major mechanical problems if you don't immediately shut off your vehicle's engine. 

Blocked Condenser Drain

The air conditioner has a condenser drain, which can cause moisture problems inside your vehicle if the drain is blocked. Many people don't know this, but your vehicle uses the air conditioner when you turn on the defrost. The air conditioner is used because it also acts as a dehumidifier. However, the system will not work effectively if the condenser in the air conditioning system is blocked, because the moisture will not be able to move through the blockage.

If this is your problem, you may notice a musty odor when you turn on your air conditioner or your defrost. To clear up this problem, you'll need to unblock the drain. If you are mechanically inclined, you can blow some air through the drain with an air compressor. Otherwise, hire a mechanic to remove the blockage.