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does anybody know what causes vehicles to frost on the inside of the windows in the winter time. My brother just wants to know and i couldnt give him a good answer
Codensation caused by warm moist air hitting the cold surface of the glass. As warm air cools it cannot hold as much moisture so it has to release it on any surface it touches, it will show up the most on the glass.
In winter I always crack open a window an inch or so to let some of the warm moist air escape and also to let the heater work better.
With the windows closed the heater bringing in fresh air will build up a possitive pressure inside the vehicle reducing it ability to bring in more warmed air.
Is everybody is confused enough?
Fom's got it right. That's precisely it. As for the A/C thing, that's correct as well. My Dad does appliance repair as well as auto A/c and the newer units automatically run the a/c for a short time when defrost is turned on.
Does this frosting on the inside accumulate while you drive, or is it there before you start the vehicle up?
I've had it accumulate after startup if you get snow blowing through your heater core.
If it's there before I start the vehicle, it was usually from too much moisture already in the vehicle, like from too much snow on the floor, that kind of thing.
Either way it's the same principle. warmer moist air hits cooler winshield and drops it's moisture. If the winsheild isn't too cold, it just fogs up, if it's cold enough to freeze, thenit frosts up. That help???
Just like Fom said.... and my '72 does the same thing now because I blocked the fresh air intake to get more heat.
Depending on the weather, I can be seen scraping the windows from the inside at stoplights