In autumn rain, can't see clearly in the car, turn on cold air or warm air?

[SanCecilia]

Both cold air and warm air can solve this problem. Defogging with cold air: When the windshield fogs up, the most effective method is to turn on the air conditioning (A/C) for cooling, activate the external circulation, set the air direction to blow towards the windshield, and adjust to the maximum fan speed. This way, the dry cold air will directly blow onto the windshield, forming a 'gas film' on the surface that prevents water vapor from condensing on the glass. In less than a minute, even the thickest fog will disappear. Defogging with warm air: The method is the same as with cold air defogging, except you don't turn on the cold air but instead blow warm air onto the glass. Using warm air to defog the glass is more effective than cold air, as it essentially dries the water vapor, eliminating concerns about secondary fogging. However, warm air defogging is slower than cold air, and the fog may initially worsen when first turned on.