Which Button to Press for Windshield Fogging?

[OEloise]

Press the defogging button, turn on the air conditioning cooling (A/C) switch, set the temperature to the lowest, and turn on the external circulation to defog. You can use either cold or warm air to defog the car windows, but warm air is slower than cold air. The most effective method is to use cold air, which blows dry cold air directly onto the glass, preventing water vapor from condensing on the glass and achieving the purpose of defogging. The method for defogging with warm air is the same as with cold air, but note that warm air should not be used for defogging on rainy days, as it will initially increase fogging. When the car windows fog up, turn on the external circulation. The reason for car window fogging: There is a certain temperature difference between the inside and outside of the car. If the temperatures inside and outside the car are different, the surface of the side with the lower temperature will have a lower saturated vapor pressure than the surrounding environment, causing water vapor to gather on the glass surface and form tiny water droplets, resulting in fogging. Methods for defogging car windows: Air Conditioning Cooling: Use the air conditioning's cooling and dehumidifying function to reduce air humidity and remove fog. In summer, especially when multiple people enter the car and the air conditioning is not turned on in time, the high humidity of exhaled air can quickly cause the windshield to fog up. At this point, you can turn on the air conditioning to blow cold air onto the windshield, using the dehumidifying function to quickly remove the fog. If the humidity is too high and the air conditioning is not effective, you can slightly open the window to quickly reduce the humidity inside the cabin. Of course, combining this with the air conditioning will yield faster results. Air Conditioning Warm Air: Use the method of reducing the temperature difference to remove fog. In winter, blowing warm air onto the glass quickly raises the temperature of the windshield, reducing the temperature difference between the inside and outside surfaces of the glass, thereby preventing excessive fogging. However, it should be noted that the rear and side windows heat up more slowly, so it takes longer to completely remove the fog. Whether the air conditioning is automatic or manual, turning it on helps with dehumidification. The temperature control should not be set to the coldest position, as this can cause the outer surface of the windshield to fog up over time. Applying Anti-Fog Agents for Prevention: Spray a small amount of defogging agent on the car windows and wipe it clean to remove dirt and stains. While polishing the glass, a thin transparent protective film is formed, effectively preventing water vapor from condensing on the glass and forming fog, which is especially useful in cold winters. Alternatives to defogging agents include dish soap, soapy water, glycerin, alcohol, or salt water. After applying and letting it dry, wipe off any excess with a chamois or soft dry cloth to ensure the windows remain fog-free for several days. Opening Windows for Airflow: If the fog inside the car is not too heavy, you can open the windows on both sides to allow air to flow between the inside and outside of the car, reducing the temperature difference and gradually eliminating the fog. The principle of this method is the same as using cold air from the air conditioning. The downside of opening windows for airflow is obvious: it cannot be used during rain, snow, on highways, or when the fog is heavy. Rear Window Heating: Most cars have a rear window heating function, though the button location may vary. Turning on the rear window heating switch will remove the fog in about a minute.

[SanVivian]

I've encountered foggy windshields countless times while driving, especially on rainy days or winter mornings. The solution is actually quite simple: locate the button on the air conditioning control panel marked with a windshield icon, usually accompanied by a fan or defrost symbol – that's specifically designed for this purpose. Press it, and the AC will automatically increase fan speed to blow away the fog while switching to external air circulation to bring in dry air. Fogging mainly occurs due to high interior temperature meeting cold glass, causing water vapor to condense. After pressing the button, remember to set the temperature around 20°C – not too high to prevent persistent fogging. Prevention matters too: clear snow/water from windows before driving, avoid leaving damp clothes inside, and replace AC filters regularly. If sudden fogging occurs while driving and doesn't clear quickly after using the button, activate hazard lights and pull over safely – never risk driving impaired. Safety always outweighs haste, and making this a habit saves considerable trouble.