How to Deal with Foggy Car Windows While Driving?
3 Answers
Press the defogger button, turn on the air conditioning (A/C) switch, set the temperature to the lowest, and turn on the external circulation to defog. Foggy car windows can be cleared by using either cold or warm air, 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 will initially worsen the fog. When the car windows are foggy, external circulation should be turned on. The reason for 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 of the side 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 droplets, resulting in 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 many people enter the car and the air conditioning is not turned on in time, the humidity of the exhaled air is high, and the windshield will quickly fog up. At this time, you can turn on the air conditioning to blow cold air onto the windshield, using the air conditioning's dehumidifying function to quickly remove the fog on the windshield. 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, it can also be used in combination with the air conditioning for faster results. Air Conditioning Warm Air: Use the method of reducing the temperature difference to remove fog. In winter, use warm air to blow hot air onto the glass, quickly raising the temperature of the front glass and reducing the temperature difference between the inner and outer surfaces of the window glass, which can promptly prevent excessive fogging on the windshield. However, it should be noted that the rear and side windows heat up 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, otherwise, the outer surface of the windshield may fog up after prolonged use. Spraying 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 from the glass. While cleaning the glass, a thin transparent protective film is formed on the glass, which effectively prevents water vapor from condensing on the glass and forming a fog layer, making it especially suitable for cold winters. Alternatives to anti-fog agents include dishwashing liquid, soapy water, glycerin, alcohol, or saline solution. After drying, use chamois or a soft dry cloth to wipe off any excess fibers, which can keep the car windows fog-free for several days. Opening Windows for Airflow: If the fog inside the car is not 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 allowing the fog to slowly disappear. 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 in rainy or snowy weather, 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.
As a veteran driver who frequently takes long-distance trips, I have plenty of experience with foggy windows. This situation most commonly occurs in winter, primarily due to the temperature difference between the inside and outside of the car. The most effective method is to turn on the air conditioning defogging function, set the fan to maximum speed aimed at the windshield, and remember to press the AC button for dehumidification. Cold air defogs quickly, but if it's too cold, you can switch to warm air, though it may take a few extra minutes. Opening the windows slightly for ventilation is also a simple emergency solution, or you can use professional defogging spray to wipe the glass. It's important to keep the interior of the car as dry as possible and avoid bringing in too much moisture. When dealing with foggy windows, always choose a safe place to pull over and handle the situation, as sudden fogging while driving can easily lead to accidents.
I encounter this issue during my daily commute and have summarized some practical tips. The first thing to do after getting in the car is to turn on the defogging mode of the air conditioner and adjust the airflow direction specifically towards the windshield. It is recommended to alternate between cold and warm air for the air conditioner: use cold air for quick defogging when the temperature is high, and warm air for comfort in cold weather. If the rearview mirror fogs up, you can spray glass cleaner on a cloth and gently wipe it. During heavy rain, I spray anti-fogging agent on the inside of the windshield in advance, and the effect can last for several days. Additionally, it is advisable to check if the air filter is dirty and replace it regularly to ensure dehumidification efficiency. In urgent situations, use a towel to wipe, but make sure to stop the car for safety.
