Should You Use Hot or Cold Air to Defog a Car?

[LaJuliana]

Cold air should be used to defog the car, as detailed below: 1. The key to defogging is to equalize the temperature on both sides of the glass or to raise the surface temperature of the glass itself to prevent fogging. 2. The most common method to deal with foggy windshield on rainy days is to turn on the air conditioner and direct the airflow to the front windshield. The cold air quickly disperses the fog upon contact with the glass, providing fast and direct results. This is because the cold air forms a 'cold air film' on the glass surface, preventing carbon dioxide from condensing on the glass and thus achieving the defogging effect. 3. In cold weather when using the air conditioner is not suitable, it is recommended to switch to the external circulation mode and adjust the airflow to direct all air towards the glass, which will moderately alleviate the fogging.