Hi all.
I’ve lived in the north of the U.S. all my life, and I’ve been driving in it for 20 years. This year, my car is doing something odd. The frost forms on the inside of the windshield instead of the outside.
Which makes it harder to scrape off and when it melts, I can’t use the windshield wipers to get rid of the water. I have to use a towel which leaves streaks. (I’ve been planning on getting Windex and some paper towels to keep in the car).
Anyway, does anyone know why this is happening?
Do you have any leaks anywhere? If there is any moisture inside the car, like snow from your feet on the floormats, it evaporates and leaves a film on your windshield.
Normally the cars heater uses cool, dry, outside air to defrost and heat the inside of the car during winter. For some reason your car sounds like it is recirculating the inside air, which is most, and warm, from your own body, being in the car. Check your heater control to make sure it isn’t in the recirculate mode, which is used to run the air conditioning in the summer.
If it isn’t in the recirculate mode, then there is something wrong with the heater, because it isn’t sucking in outside air, and a mechanic would have to look at it.
Too much moisture inside the car.
Is it a 20yo car?
It can happen from the snow on your boots and such, if it’s sunny out during the day, your car turns into a hot house. The moisture condenses on cold surfaces like windows, and freazes during the night.
Or, a leak in your heater core. But from your description, I sorta doubt it. You would be putting a mixture of anti-freeze and water on your windshield when you use defrost, you would smell the anti-freeze. It’s sorta a sickly sweet smell.
It may well be a clogged drain line in your, ummm, heater box. On newer cars, with defrost on, the heat AND air-conditioner runs to remove moisture from the air. The water drips off the evaporator (probably not using the right terms here) and drains out through a hose. If the hose gets clogged, the water remains in the heater box, and the warm air sucks up the water and puts very moist air in the car, that can freeze later.
If it’s just from snow on your boots, and you park in the sun during the day, crack your windows to get some of the moisture out of the car.
If it’s the heater core, that’s gonna be a bit expensive.
If it’s the drain line, it should be a cheap fix.
-----Also, some cars have the option of using outside or inside air for the heating/cooling system (recirculate or not). You want to use outside air as much as possible, this will put fresh, less humid air in your car.
But… you also have to consider that there may be snow in the incoming vents(outside air). In that case a mixture of snow and air will hit the heater core, causing some very, very moist air to enter your car.
I’m sure another doper will come along soon with a better description.
If you turn on the AC and run that through your heater, it will dry out the inside of your windshield more quickly than just the defroster.
I don’t have the option of running the heater with internal air. And my AC doesn’t work.
But i’ll try cracking the windows. I do tend to get quite a bit of snow in there during the winter.
Thanks.