Press the defogging button, turn on the air conditioning (A/C) switch, set the temperature to the lowest, and use the external air circulation to defog. Both cold and warm air can be used to defog the car glass, 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 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 on rainy days as it may initially worsen the fogging. When the car glass fogs up, external air circulation should be used. The reasons for fogging on car glass: 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 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 to defog car glass: Air Conditioning Cooling: Use the air conditioning's dehumidification function to reduce air humidity and remove fog. In summer, especially when multiple people enter the car, if the air conditioning is not turned on in time, the high humidity from exhaled breath can quickly cause fogging on the windshield. At this time, you can turn on the air conditioning and blow cold air onto the windshield, using the dehumidification function to quickly remove the fog. If the humidity is too high and the air conditioning is not effective enough, 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 can quickly raise 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 may cause fogging on the outer surface of the windshield over time. Applying Anti-Fog Agents for Prevention: Spray a small amount of anti-fog agent onto 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 and forming fog. This is especially useful in cold winters. Alternatives to anti-fog agents include dish soap, soapy water, glycerin, alcohol, or saltwater. After applying, let it dry and then wipe off any excess with a chamois or soft dry cloth. This can keep the car glass fog-free for several days. Opening Windows for Airflow: If the fog inside the car is not too heavy, you can open the side windows to create airflow between the inside and outside of the car, reducing the temperature difference and slowly dissipating the fog. The principle of this method is the same as using cold air from the air conditioning. However, the downside of opening windows is very obvious: it cannot be used during rain, snow, on highways, or when the fog is too heavy. Rear Windshield Heating: Most cars have a rear windshield heating function, though the button location may vary. Turning on the windshield heating switch will make the fog on the rear windshield disappear in about a minute. Using External Air Circulation: On rainy days in spring and autumn, opening the windows may not be suitable, and turning on the air conditioning may feel too cold. At this time, you can use external air circulation and adjust the air vent to blow onto the windshield. This quickly lowers the temperature on the inner side of the windshield, making the fog disappear quickly.
