What Type of Air Should Be Turned On When Car Windows Fog Up on Rainy Days?
2 Answers
On rainy days when car windows fog up, you should turn on the cold air. Cold Air Defogging: The most common method to deal with fogged-up windshields while driving in the rain is to turn on the air conditioning and direct it toward the front windshield. The cold air blowing onto the glass quickly disperses the fog, providing a fast and direct effect. This happens because the cold air creates a 'cold air film' on the glass surface, preventing carbon dioxide from condensing on the glass and thus achieving the defogging effect. Window Ventilation: If the fog inside the car is not too heavy, you can slightly open the windows on both sides to create an airflow between the inside and outside of the car. This reduces the temperature difference and slowly dissipates the fog. The principle of this method is similar to turning on the cold air, but it does not increase fuel consumption. However, window ventilation has obvious drawbacks: it is not suitable during rain, snow, or on highways when the fog is heavy, and it also lowers the temperature inside the car.
I'm someone who often drives in rainy weather, and foggy windows are a common occurrence, especially when the humidity is high on rainy days. In such situations, I immediately turn on the air conditioning, set the airflow to the front windshield, and switch to the external circulation mode. External circulation brings in dry air, and the air conditioning compressor works exceptionally well for dehumidification. Remember to avoid using only internal circulation or hot air, as hot air can sometimes worsen the fogging. Once, I was in a hurry, and the windshield was so fogged up that I couldn't see clearly. I mistakenly turned on the hot air, which made it even worse—I nearly had an accident! So now, I make it a habit to first set the external circulation mode, adjust the fan speed to medium, and maintain a moderate temperature inside the car. I also regularly clean the oil film on the windows to reduce the risk of fogging and try to keep the windows closed as much as possible on rainy days to avoid excessive moisture entering the cabin. Fogging is no trivial matter—it's about driving safety, and everyone should take it seriously.
