Hot air or cold air to demist the inside of a windscreen when its cold outside?

Question

Because isnt it our body heat that makes it fog up?

Answer 1

If your windshield is fogging up you need to let fresh air in the car. Open the air vent to fresh and not recycled or recirculate. Most newer cars use a mixture of heat and air conditioning when you use the defrost setting. The fresh air mix helps take out moisture from the air which causes the fogging up on the inside.

Answer 2

Hot air. Two things happen when you turn on your defroster. If your car has Air Conditioning the A/C compressor automatically turns on and the fan blows air through the ductwork at the bottom edge of your windshield.
Having the AC compressor come on lowers the humidity of the air being blown, having the air hot lowers it further so the moisture on your windshield can evaporate more easily and clear your view. By chance, if your windshield keeps fogging over worse and worse, and you smell antifreeze, you have a small leak in your hearter core and need it replaced. It doesn't sound like you have this problem though.

Answer 3

My owner's manual suggests running the air conditioner until the windscreen/windshield dries off and then switch to warm air.

Answer 4

A little known (or realised) fact about car air conditioners is that they are reverse cycle. In other words, the air conditioner (not the heater) can warm you up as well as cool you down.

So, just use the air conditioner on the defrost mode.

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Answer 5

Put on defrost with warm or hot air.

Answer 6

Hot air to defog the windows when it is cold out.

Answer 7

Demist