Frost appearing inside the car?

Is your heater set to recycle the air in the car? If so, set it to heat the fresh air coming in. Also, set the heat to hot, but turn the air conditioner on. The air conditioner acts as a dehumidifier in the winter time. The air conditioner will not cool unless the temperature is set to cool.

First red flag and question to you is this: has your car ever been in an auto accident? generally, this is the case, when inside frost on the windows is hard to make go away.

If your car is well-heated inside, by the cars heater and frost is still there, start searching for damp areas on the floorboard and especially in the cars trunk. inside moisture is a dead giveaway of an auto thats been involved in an accident.

My wifes car is the same way. before we purchased her Honda, we had no idea that her vehicle had been rearended in an auto crash. the first winter and inside window frost brought out the truth and we located moisture in the Hondas trunk.

turn on your defroster, and open the drivers window, and the passenger window. Drive around.
If the carpets are wet, turn on the floor heater. you might have a leak in your front windshield seal.

In most (I think) cars turning the knob to Defrost also turns on the air conditioner, to dry the air.

My old car did that as well. I had a scraper for the inside. I wore more clothes to drive somewhere than most people did for a long walk. However, it started in 40 below weather. The dealership and garages told me I needed a new heater.

Of course there is moisture, you breath in there, don’t you. The moisture from your breath is drawn to the windows and freezes. My advice, stop breathing in the car.

If you breath, there is moisture in the car.
If you track snow into the car or get in with wet clothes (maybe because it’s raining) there is moisture in the car.
Actually, there are many innocuous ways that moisture can get into a car, as well as a few sinister ones like my leaky sunroof.

How to solve it depends on which problem you actually have.

I live in a cold climate. Moisture gets in from your breath, or the snow on your feet, or leakage around the window, or heater core, or…
When driving put the heat on and try to dry out what you can. Then…

During the last mile before reaching our destination or home we turn off our heater and lower the window to let the warm, moist air out and bring the cold dry air in. That helps a lot.

I’m not sure where you’re from, but this happens all the time in places where it’s cold and snowy. I’ve found that the best way to deal with it is to leave the windows open a crack when the car is parked (if you park in a safe location). That seems to help a bit – otherwise, I just deal with it. It’s a part of having a car, as far as I’m concerned.

Interesting that you would post this question. My daughter recently started having the same problem. Her back window started forming ice on the inside overnight. My son the auto mechanic thinks the seal around her rear window is at fault. Sounds like you might have a bad seal around your windshield. Of course your windows are going to fog up when you are running the heater and the frost on the inside of your windshield melts! Run the defroster, which all of us who live in cold climates have to do all winter. And have the seal around your windshield checked.

@Seelix It doesn’t happen with the car I have now. It’s not moisture I had in my Acadian, it was thick, white frost that had to be scraped off. I haven’t seen it since or heard people complain of it until now. There is something wrong with the heater as in no heat!!

@faye – Huh. It’s always happened to me. I’ve always had to park outdoors, though – my parents’ cars in the garage were always fine.

@Seelix They are going to tell us to get a room! I am 56, parked outside all of my working life, my car now doesn’t do that to me. “Should’ve bought a Mercury”....

temperature inside and outside the car are different that’s why it created a moist on your windshield