How to Deal with Foggy Car Windows When Using Air Conditioning in Winter?

[Rex]

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 remove fog. 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 should be noted that warm air should not be used for defogging on rainy days, as it may initially increase fogging. When car windows fog up, external circulation should be turned on. 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 colder side 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 fog. Methods to defog car windows: Air conditioning cooling: Use the air conditioning cooling and 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 in time, the high humidity of exhaled air can quickly cause the windshield to fog up. At this time, turn on the air conditioning to blow cold air onto the windshield, using the dehumidification function to quickly remove fog. If the humidity is too high and the air conditioning is not effective, slightly open the window to rapidly 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, blow warm air onto the glass to quickly raise the temperature of the windshield and reduce the temperature difference between the inner and outer surfaces of the window, 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 air conditioning temperature control should not be set to the coldest position, as this may cause frost to form on the outer surface of the windshield 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 anti-fog agents include dishwashing liquid, soapy water, glycerin, alcohol, or salt water. After drying, use a chamois or soft dry cloth to remove excess fibers, ensuring the car windows remain fog-free for several days. Opening windows for convection: If the fog inside the car is not too heavy, you can open the windows on both sides to create convection between the inside and outside air, 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 convection is obvious: it cannot be used during rain, snow, on highways, or when the fog is heavy. Rear window heating: Most cars are equipped with a rear window electric heating function, though the button positions may vary. Turn on the rear window heating switch, and the fog on the rear window will disappear in about a minute.