Why Does Turning on Defogging Actually Increase Fogging?
2 Answers
It might be because the air conditioning is set to recirculate. When there are people breathing inside the car, the humidity increases, and if the outside temperature is low, the warm, moist air can condense on the cold glass, causing fogging. Switching the heating to fresh air mode can help avoid this issue. More related information is as follows: 1. Fresh Air Mode: To defog, use fresh air mode, which involves heating or cooling the air from outside the car before bringing it inside, thus exchanging air between the inside and outside of the vehicle. Recirculation mode means the air inside the car is heated or cooled and then circulated back inside. 2. Car Air Conditioning: Car air conditioning typically includes cooling, heating, and ventilation systems. This integrated setup makes efficient use of the limited space inside the car, featuring a simple structure and easy operation, making it the internationally popular modern car air conditioning system. Car air conditioning can cool, heat, ventilate, and purify the air inside the cabin, providing passengers with a comfortable environment, reducing driver fatigue, and improving driving safety.
Sometimes when I turn on the defogger while driving, the fog actually gets worse. This is because the hot air blown out when the air conditioning system first starts up is more likely to condense moisture on the cold windshield. The humidity inside the car is high, especially when you first get in and it's cold outside but warm inside. The defogging mode needs time to dry the air. The correct approach is to press the AUTO button or turn on the AC when using the air conditioning to defog, as this helps reduce humidity while adjusting the temperature to avoid a large temperature difference. It also depends on the humidity outside—for example, keeping windows closed on rainy days to prevent external moisture from entering, or warming up the engine before using the heater in winter. Check that the air filter isn’t clogged, as poor airflow can hinder defogging, and don’t forget regular maintenance. Common mistakes include blowing air directly at the windshield without turning on the AC or using a fan speed that’s too low, resulting in insufficient airflow. It’s recommended to initially set the fan to medium or high speed to speed up dehumidification. In short, experiment with temperature adjustments and air conditioning settings to improve the situation.
