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. 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 for defogging on rainy days, as it may initially increase fogging. When the car glass fogs up, the external circulation should be turned on. The reason 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 of the side with the lower temperature will have a saturated vapor pressure lower than the surrounding environment's vapor pressure, 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 and the air conditioning is not turned on promptly, the exhaled air has high humidity, and the front windshield will quickly fog up. At this time, you can turn on the air conditioning to blow cold air onto the front windshield, using the dehumidification function to remove the fog quickly. However, 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 car. 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 front glass, reducing the temperature difference between the inner and outer surfaces of the window glass, thereby preventing excessive fogging on the front windshield. However, it should be noted that the rear and side glass temperatures rise more slowly, so it takes longer to remove all the fog. Whether the air conditioning is automatic or manual, turning it on helps with dehumidification. The air conditioning temperature control should not be set to the coldest position, as this may cause the outer surface of the windshield to fog up over time. Spraying Anti-Fog Agents for Prevention: Spray a small amount of defogging agent on the car glass 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. This is particularly suitable for cold winters. Alternatives to defogging agents include dish soap, soapy water, glycerin, alcohol, or salt water. After applying and letting it dry, use a chamois or soft dry cloth to wipe off any excess residue, ensuring the car glass remains 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 gradually dissipating 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 very obvious—it cannot be used during rain, snow, on highways, or when the fog is heavy. Rear Windshield Heating: Most cars have a rear windshield electric heating function, although the button locations may vary, the function is the same. Turn on the windshield heating switch, and the fog on the rear windshield will disappear in about a minute.
