Which Button to Press for Foggy Windows on Rainy Days?
2 Answers
Press the defogging button, turn on the air conditioning cooling (A/C) switch, set the temperature to the lowest, and activate the external circulation to defog. Both cold and warm air can be used to defog car windows, but warm air is slower than cold air. The most effective method is using 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 of using warm air to defog is the same as using cold air, but it should be noted that warm air should not be used for defogging on rainy days as it may initially worsen the fog. Always use external circulation when defogging car windows. The reason for foggy car windows: 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 with the lower temperature will have a saturated vapor pressure lower than the vapor pressure of the surrounding environment, causing water vapor to gather on the glass surface and form tiny water droplets, resulting in fog. Methods to defog 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 promptly, the exhaled air has high humidity, causing the windshield to fog up quickly. At this point, you can turn on the air conditioning to blow cold air onto the windshield, using the dehumidifying function to remove the fog shortly. If the humidity is too high and the air conditioning is not effective enough, you can slightly open the windows to quickly reduce the humidity inside the car. Of course, combining both methods 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 inner and outer surfaces of the window glass, thereby preventing excessive fogging of the windshield. 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. Do not set the air conditioning temperature to the coldest position, as this may cause frost to form on the outer surface of the windshield over time. Applying Anti-Fog Spray 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 saline solution. After applying, let it dry and then wipe off any excess fibers with chamois or a soft dry cloth. This can ensure the car 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 create airflow between the inside and outside of the car, reducing the temperature difference and allowing the fog to dissipate slowly. The principle of this method is the same as using cold air from the air conditioning. The downside of opening windows for airflow is very obvious—it cannot be used during rain, snow, on highways, or when the fog is heavy.
I remember once driving in the rain when the windshield fogged up completely white—couldn't see a thing, scared me half to death. Later I figured out you just need to press that fan icon button on the center console, usually marked with a defrost symbol. Some cars might also require turning on the AC and selecting cold air aimed at the glass or turning up the temperature a bit—defogs super fast. Best to crack the window slightly or switch to outside air circulation to let the humidity escape. Don’t just focus on driving and forget safety. Pro tip: regular car washes and using anti-fog spray on the glass can reduce trouble. Next time I encounter fog, I’ll hit that button immediately—guaranteed clear vision and much more comfortable driving.
