How to Deal with Foggy Side Windows on a Rainy Day?
3 Answers
Press the defogging button, turn on the air conditioning cooling (A/C) switch, set the temperature to the lowest, and use the external circulation to remove fog. Both cold and warm air can defog car windows, but warm air works slower than cold air. The most effective method is using cold air, which blows dry cold air directly onto the glass, preventing water vapor from condensing on the glass and achieving defogging. The method for warm air defogging is the same as cold air, but note that using warm air on rainy days may initially worsen the fog. Always use external circulation when defogging car windows. The reason for car window fogging: There is a temperature difference between the inside and outside of the car. If the temperatures differ, the surface with the lower temperature has 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 for 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 without turning on the air conditioning, the exhaled humid air can quickly cause the windshield to fog up. Turning on the air conditioning to blow cold air onto the windshield and using the dehumidification function can quickly remove the fog. If the humidity is too high and the air conditioning is ineffective, slightly opening the windows can quickly reduce the humidity inside the car. Combining both methods can yield faster results. Air Conditioning Warm Air: Use warm air to reduce the temperature difference and remove fog. In winter, blowing warm air onto the windshield quickly raises its temperature, reducing the temperature difference between the inside and outside surfaces and preventing heavy fogging. However, the rear and side windows heat up slower, so it takes longer to remove all the fog. Whether the air conditioning is automatic or manual, turning it on helps with dehumidification. Avoid setting the temperature to the coldest to prevent frost on the outside of the windshield. Applying Anti-Fog Agents: Spray a small amount of defogging agent on the car windows and wipe it clean to remove dirt and stains. This leaves a thin transparent protective film that effectively prevents water vapor from condensing on the glass, especially useful in cold winters. Alternatives to defogging agents include dish soap, soapy water, glycerin, alcohol, or salt water. After applying and letting it dry, wipe off any excess with a soft cloth to keep the windows fog-free for several days. Opening Windows for Airflow: If the fog inside the car is not too heavy, opening the side windows can create airflow between the inside and outside, reducing the temperature difference and gradually eliminating the fog. This method works on the same principle as using cold air from the air conditioning. However, it has obvious drawbacks and cannot be used during rain, snow, on highways, or when the fog is heavy. Rear Window Heating: Most cars have a rear window heating function, though the button location may vary. Turning on the rear window heating switch will clear the fog in about a minute.
The other day I was driving in the rain when the side windows fogged up, and it took me a while to figure it out. The large temperature difference on rainy days causes moisture inside the car to condense on the cold glass, forming fog. The solution is simple: after starting the car, turn on the air conditioning in defrost mode (press the small fan icon), and it doesn’t matter whether you use cold or warm air—the fog will clear in seconds. Worried about the air conditioning using too much fuel? Turn on the external air circulation to keep the air flowing and drier. It’s also a good idea to keep a bottle of anti-fog spray in the car, which you can buy for a few dollars at the supermarket—just spray and wipe for excellent fog prevention. For prevention, regularly clean the inside of the windows with a soft cloth to avoid dust and grease buildup. If fog forms while driving, don’t rush—pull over to handle it safely. Once you develop these habits, driving in the rain becomes much smoother.
Having played with cars for years, I've found that the core of side window fogging lies in humidity and temperature control. Using the external air circulation is most effective on rainy days, reducing humidity fluctuations inside the car. The defogger button is a powerful tool – just blast it at the windows for a while to clear the fog. If you want to save battery, the old-school method works too: open the windows for a few seconds to balance the temperature difference, but don't leave them open too long in the rain to avoid getting wet. When using anti-fog spray, remember to wipe it evenly. A homemade trick is to dilute dish soap and apply it to the glass. For maintenance, keep the interior dry with some desiccant. Safety first – fogged windows impair visibility and can lead to accidents, so always check the defogging function before driving in the rain. Long-term, keeping windows clean to prevent dirt buildup is key.
