The inside of the car fogs up and on very cold mornings ice forms

a fix for this is to run the ac
this although make it cold removes the moisture from the air inside the car and reduces the fogging up
if you have climate control run it or if not run the heater at the same time to take the edge of the cold
The air conditioner works by removing water vapor from the air through a condensation process there by making the air feel cooler
that restricts the moisture available to fog up the windows

This is normal if your A/C doesn't work. When set on defrost the A/C kicks on and off to keep the fog from appearing. the fog goes away once the heat inside reaches a certain temperature. Unless the drain is clogged and the plenum is holding water. Do you have ice on the inside? clean the drain. It's on the passenger side, near the bottom of the firewall. A rubber tube coming out, that goes to nothing.

try running the ac as well as the heater. The ac removes the humidity (water vapour) in the air in the car which is causing the fogging up . Hot moist air on glass creates fog ( same as clouds). You will get a comfortable temperature inside without the fog

This may be due to a bad heater core or dirty core with a plugged water drain, first see if the a/c works. turn it on and see if the air gets cold and if the ac compressor works.

The way the defrost works to keep windows from fogging up is that when the front defroster is tuned on the ac should also be on, on most cars when you go to defrost it will turn ac on automatic. the system then uses hot and cold air to remove the moisture in the air to avoid window fogging. if your a/c is not working then that may cause window to fog, but if you are also getting a smell then the drain that lets out condensation may be plugged and then water builds up and also mold from always being wet and when heat is on you smell that.


i want you to run the defrost and when windows fog up wipe window with hand and see if it is greasy . if it feels oily then you may have a bad heater core, the core leaks coolant out and steam and causing windows to fog up with a flim of grease.

A simple fix is to clean the windows, then apply a coat of white shaving cream. The cream stops fog build up. Simple rub it in then wipe it off.

IN COLD WEATHER USE BI LEVEL AND TURN ON HEAT ON AC AND HEATER MODE SWITCH AND HEAT MODE THAT WILL KEEP WINDOWS FROM FOGGING UP KEEP CAR WARM ON THE INSIDE WHEN COLD OUT SIDE ALWAY CARRY PAPER TOWER OR SOME THING TO WIPE WINDOWS WHEN FOG UP MOST TIME I HAVE PROBLEM WINDOWS FOGGING UP WHEN YOU HAVE COLD RAIN OUT SIDE.IF WINDOWS FOG REALLY BAD I HAVE TO TURN MODE SWITCH TO COLD MODE AND TURN ON DEFOGGER.

Yes. Unless you get fresh air you will fog up your windows. Your breath or rain on your clothes or snow on your boots will all cause the humidity to increase and this moisture will deposit on the non insulated glass. Kind,of like a glass of ice tea on a warm day you will get a condensation on the glass. The temperature difference is the cause. Try to run your A/C with the temp set to hot. This will act as a dehumidifier.
also check your pollen filter make sure it's not clogged.

You may have a heater core leak in the passenger compartment. It will add moisture to your inside and do just what you describe.

I usually just put the A/C on, even though at night/early morning it gets a bit cold.