Which Button to Press for Car Window Fogging?

[Wade]

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 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 of using warm air to defog is the same as using cold air, but it is important to note that warm air should not be used for defogging on rainy days as it may initially increase fogging. Always use external circulation when car windows fog up. 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 with the lower temperature will have a lower saturated vapor pressure than the surrounding environment, causing water vapor to gather on the glass surface in the form of tiny droplets, forming 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, and the windshield will fog up quickly. At this time, you can turn on the air conditioning to blow cold air onto the windshield, using the dehumidifying function to remove the fog quickly. If the humidity is too high and the air conditioning is not effective, you can slightly open the windows 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 window 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 remove all 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 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 dishwashing liquid, soapy water, glycerin, alcohol, or salt water. After applying, let it dry and then wipe off excess residue with a chamois or soft dry cloth. This will keep the car windows 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 eliminating the fog. The principle of this method is the same as using cold air from the air conditioning. However, 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 Window Heating: Most cars have a rear window electric heating function, although the button positions may vary, the function is the same. Turn on the rear window heating switch, and the fog on the rear window will disappear in about a minute.