Which Button to Press for Foggy Car Windows?

[HarleyMarie]

Causes of 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 lower saturated vapor pressure than the surrounding environment, causing moisture to gather on the glass surface and form tiny droplets, resulting in fog. Methods to defog car windows: For manual air conditioning, turn on the front window defogging mode, set the fan speed to maximum, turn on the A/C switch, and then set the temperature to the lowest. Wait a moment, and the fog on the windows will disappear. Some models are equipped with rear window electric heating and external rearview mirrors; simply press the switch, and the fog will clear in about a minute. For automatic air conditioning, generally just press the one-touch defrost button, set the fan speed to maximum, and turn on the external circulation. The fog on the car windows will disappear shortly. Press the defog button, turn on the 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, as it blows dry cold air directly onto the glass, preventing water vapor from condensing and achieving defogging. The method for warm air defogging is the same as cold air, but note that warm air should not be used on rainy days, as it may initially worsen the fog. Always use external circulation when defogging car windows. 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 promptly, the high humidity from exhaled breath can quickly cause the windshield to fog up. In this case, turn on the air conditioning to 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 ineffective, slightly open a window to rapidly reduce the humidity inside the cabin. Combining this with the air conditioning will yield faster results. Air conditioning heating: 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 front windshield, reducing the temperature difference between the inside and outside surfaces and preventing excessive fogging. However, note that the rear and side windows heat up more slowly, so it takes longer to completely remove the fog. Whether using automatic or manual air conditioning, turning it on helps with dehumidification. Avoid setting the air conditioning temperature to the coldest setting, as prolonged use may cause the outer surface of the windshield to fog up. Applying anti-fog spray or other preventive measures: Spray a small amount of defogging agent onto the car windows and wipe it clean to remove dirt and stains. While polishing the glass, a thin transparent protective film forms, effectively preventing moisture from condensing on the glass and forming fog. This 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 excess residue with chamois or a soft dry cloth. This will keep the windows fog-free for several days. Opening windows for convection: If the fog inside the car is not too thick, you can open the side windows to allow air convection 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. However, the drawbacks of opening windows for convection are obvious: it cannot be used during rain or snow, on highways, or when the fog is too heavy.