How to Turn on Defogging on Rainy Days?

[DelRose]

First press the A/C switch button, then turn on the front windshield defogging button, set the temperature to the lowest, and adjust the air volume to eliminate fogging. When the car is just started, do not turn on the air conditioning immediately. After the water temperature rises, start heating, turn the air volume to the maximum, and press the defogging button to make the fog disappear.

[VonGraham]

Driving in rainy weather with a foggy windshield is particularly annoying and affects safety. Having driven for over 10 years, I deal with this situation immediately: After starting the car, first press the defrost button on the dashboard—it looks like a small fan or is labeled 'DEF'. Then, turning on the air conditioning compressor is crucial; even if it's cold outside, it helps quickly remove moisture. Not using it may cause the fog to reappear. Switch to the external air circulation mode to let dry outside air in; internal circulation can accumulate moisture from breathing. Set the fan speed to medium or high, and adjust the temperature to a comfortably warm level, around 20 degrees Celsius is ideal. Don’t forget to turn on the rear window heating button to prevent fogging at the back. Since humidity is high on rainy days, I recommend keeping a dry cloth in the car to wipe the windows as needed. Additionally, regular maintenance of the air conditioning system, such as replacing the air filter to prevent blockages, can reduce fogging. These small details ensure clear visibility and make driving safer.

[McNova]

I remember when I first learned to drive, it was rainy and foggy, and I was all thumbs. My instructor taught me: start the engine, and the first thing is to locate the defogger button—usually the one with the front windshield symbol. Then you must turn on the AC, even in winter, as it removes moisture with immediate effect. Switch to external air circulation, not internal, or the fog will worsen. Set the fan speed higher, like above level 3, and adjust the temperature to be warmer. The first time I made a mistake, I only turned on the heater without the AC, and the fog got worse; later, with practice, I could clear it in minutes. I also found that using the wipers to clear rainwater before starting reduces external contamination that causes fogging. Beginners should find a safe spot to practice; in humid rainy weather, slightly opening the windows for ventilation works, but closing them while driving is safer. These small steps boosted my confidence a lot.

[GabriellaLynn]

As an auto mechanic, I often help customers with defogging. On rainy days, defogging is simple: press the defog button to activate the air conditioning compressor for dehumidification. Prioritize the external circulation mode to reduce humidity buildup inside the car. Set the fan to high speed, not low, because higher airflow quickly disperses fog. Vehicles with automatic air conditioning are even better—just press the AUTO button, and the system adjusts for defogging automatically. Don’t forget to clean the glass surface, as dirt makes fogging more likely. Regular maintenance of the cabin air filter is essential; replace it periodically to avoid clogging. Newer models come with humidity sensors—when fogging occurs, the auto function handles it directly, making operation even easier.