Which air circulation mode should be used when the car interior fogs up on rainy days?
3 Answers
On rainy days when the car interior fogs up, you should use the external air circulation mode. If you use the internal circulation mode, both side windows will fog up, affecting the driver's visibility. Therefore, it's recommended to use the external air circulation mode and adjust the air vents to blow towards the windshield. The external circulation mode helps expel the moisture exhaled by passengers to the outside of the vehicle, and the incoming cold air from outside is less likely to condense. The differences between internal and external air circulation modes are: 1. Different air circulation methods: Internal circulation draws air from inside the vehicle; External circulation draws air from outside the vehicle, which is then cooled or heated by the air conditioning system before being blown out through the vents. 2. Different functions: Internal circulation effectively prevents external dust and harmful gases from entering the vehicle, improving the cooling and heating efficiency of the air conditioning system; External circulation brings fresh air from outside into the vehicle to maintain air quality inside the cabin.
When I first got my driver's license, I didn't know which air circulation mode to use for defogging on rainy days. After driving more, I realized that using the external circulation mode works best. This is because the humidity outside is high on rainy days, and the internal circulation would trap the moisture inside the car, making the fogging worse. I usually press the external circulation button directly, turn on the AC for dehumidification, and increase the fan speed to blow against the front windshield. If the cabin air filter hasn't been replaced for six months, it can get moldy and reduce dehumidification efficiency, so I recommend changing it twice a year. Oh, and if the rear window fogs up, remember to press that square-shaped heating button—the effect is immediate. Once you get used to these operations, they become as natural as blinking, ensuring a clear view at all times.
Last month during heavy rain while picking up my child from school, the windshield suddenly fogged up, giving me a cold sweat. I quickly turned the knob to the external circulation mode and used the AC dehumidification function, and the fog visibly dissipated. Remember, using internal circulation in such weather can make things worse, as it recirculates the humid air inside the car. Point the air vents towards the glass, and don’t forget the rearview mirror heating function. During my last maintenance, the mechanic reminded me not to worry about fuel costs when running the AC in rainy weather—safety comes first. Now, I remotely start the car ten minutes in advance, allowing the AC system to dehumidify more thoroughly, so the view is much clearer when I get in.
