Why Does the Outside Fog Up When the Air Conditioning Is On?

[BrandonMarie]

The reason the outside fogs up when the air conditioning is on is that the temperature inside the car is lower than the temperature outside. Using the Air Conditioner to Defog: This is the simplest method. Just turn on the front window defogging mode, set the fan speed to maximum, turn on the A/C switch, and adjust the temperature to the lowest setting. The fog on the glass will disappear shortly. Additionally, some car models have heated rear windshields and side mirrors. Simply click the switch to activate them, and the fog will clear in about a minute. Using Anti-Fog Spray: To use, simply spray it evenly on the glass surface and then wipe it clean with a dry towel. Its principle is to use surfactants to form a protective film on the glass surface, altering the surface tension of water molecules so that fog droplets coalesce into larger droplets, thus not obstructing the view. This method is also suitable for other car windows, especially the side mirrors.