How to Deal with Fogging on the Car's Front Windshield in Winter?
4 Answers
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 the 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 will initially increase fogging. When the car windows fog up, the external circulation should be turned on. The reason for fogging on 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 saturated vapor pressure lower than the surrounding environment's vapor pressure, 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'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 exhaled air has high humidity, and the front windshield will quickly fog up. At this time, you can turn on the air conditioning to blow cold air onto the front windshield, using the air conditioning's dehumidifying function to remove the fog on the windshield quickly. However, if the humidity is too high and the air conditioning is not effective, you can slightly open the window to quickly reduce the humidity inside the cabin. 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 prevent excessive fogging on the front windshield in time. 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 over time. 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 polishing the glass, a thin transparent protective film is formed on the glass, which effectively prevents water vapor from condensing on the glass and forming fog. This is especially suitable for cold winters. Alternatives to anti-fog agents include dishwashing liquid, soapy water, glycerin, alcohol, or salt water. After drying, use chamois or a soft dry cloth to wipe off excess fibers, ensuring the car windows remain 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 disappear slowly. 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 Windshield Heating: Most cars have a rear windshield electric heating function, although the button positions may vary, the function is the same. Turn on the windshield heating switch, and the fog on the rear windshield will disappear in about a minute.
I find windshield fogging the most annoying when driving in the morning, especially during winter commutes. My quick solution is to first crack open the window slightly for ventilation to reduce temperature difference, then immediately turn on the warm air conditioning with airflow directed at the windshield - setting higher temperature works better. Many car models have a defog button; I press that icon to activate the automatic defogging system which clears fog within minutes. Keeping a clean cloth handy helps - if it's still blurry, I gently wipe the interior during parking breaks without distraction. Preheating the AC for 5 minutes before departure is most effective for prevention. Remember to use external air circulation to import dry air, avoiding excessive cabin humidity that causes recurring issues - this saves time and effort for daily driving.
Windshield fogging is essentially caused by moisture inside the car condensing into dew on the cold glass. Based on my experience, immediately turning on the heater with external air circulation mode to blow on the front windshield after starting the car helps reduce humidity, then switching to internal circulation maintains dryness. The AUTO button on the air conditioning system quickly adjusts airflow and temperature for efficient defogging. For prevention, avoid leaving wet umbrellas or drinks in the car to minimize moisture sources, and regularly clean the interior glass to remove grease stains as they attract moisture more easily. In winter, checking the air conditioning system is crucial; only with a properly functioning fan can reliable defogging be ensured. Developing the habit of closing windows and doors tightly when parking reduces humidity accumulation, fundamentally decreasing fogging frequency and making driving safer.
As a parent, I am particularly concerned about driving safety in foggy conditions. Once fog occurs, I immediately turn on the hazard warning lights, pull over, and wait until visibility is clear before moving again to ensure no risks are taken. After stopping, I open the windows for ventilation and use the highest setting of the warm air to blow on the windshield, which clears the fog within minutes. I educate my family to avoid bringing wet clothing into the car to maintain dryness and prevent accidents. I keep an anti-fog cloth within easy reach of the driver's seat for quick wiping in emergencies, avoiding panic. Before every trip, I check the cleanliness of the windshield to prevent oil stains from worsening fogging, always prioritizing a safe return home as the top priority.
