How to Remove Fog on Car Windows When Using Air Conditioning?
3 Answers
When fog forms on car windows while using air conditioning, you can remove it by opening windows for air convection, using the air conditioning system, or applying defogging agents. Opening Windows for Air Convection: If the fog inside the car is not heavy, you can slightly open both side windows to create air convection between the inside and outside of the car. This reduces the temperature difference, and the fog will gradually disappear. The principle of this method is the same as using cold air from the air conditioning, but it does not increase fuel consumption. However, the downside of opening windows is obvious: it is not suitable during rain, snow, or on highways, nor when the fog is heavy. Additionally, opening windows will lower the temperature inside the car. Air Conditioning System: Using the air conditioning system to remove fog is the most common method. Almost all cars nowadays have air vents below the front windshield. Simply adjust the air conditioning to the appropriate setting, and the air blown from the vents will help remove the fog. If you are in a hurry, you can use cold air for quick results. However, in most cases, it is recommended to use warm air. Turn on the car's fan and cooling switch, and the cold air directed at the front windshield will quickly dissipate the fog. The effect is immediate, but the biggest drawback is that passengers inside the car may feel cold. Defogging Agents: Spraying a defogging agent on the inner surface of the car window and wiping it clean not only removes dirt but also forms a protective film that prevents moisture from condensing into fog. One application can last for about ten days. Prices range from a few dollars to over a hundred dollars. You can also make your own defogging solution by mixing dishwashing liquid with water in a ratio of 1:10. Apply the mixture to the inside of the front and rear windshields using a clean, soft cloth, or pour it into a small spray bottle for easier application.
I often encounter the issue of foggy windows when using the AC, so here are a few practical tips. First, immediately turn up the AC fan speed and direct it toward the windshield, then press the front defrost button (the one with a扇形-shaped arrow symbol). The system will automatically switch to external circulation and blast air at the windshield. The key is to turn on the A/C cooling switch—it helps remove moisture from the car, and the fog usually clears within seconds. In summer, cold air works best, while in winter, warm air is fine too, though it may take an extra minute or two for the windshield to warm up. When stopped at a red light, I like to crack the window slightly for ventilation to balance the temperature difference inside and out. Keeping a dry microfiber cloth in the car for emergency wiping also helps, but make sure it’s a chamois cloth to avoid water streaks. Regular maintenance, like changing the cabin air filter, is crucial—a dirty filter traps moisture inside, making fogging more likely.
Don't panic when the windshield fogs up. Here's what I usually do: Press the defog button on the AC panel while turning on the A/C switch for rapid dehumidification. It's crucial to keep the air circulation in fresh air mode during rainy days, allowing dry outside air to replace the moisture inside. Adjust the AC vents to blow directly onto the windshield for instant results. For severe fogging, turn the temperature knob to maximum and use hot air—though it may initially worsen the fog, it'll clear up completely in about two minutes. Avoid leaving damp towels or wet umbrellas in the car, as they act like humidifiers in the AC environment. Have the interior glass degreased during each car wash—this cuts fogging probability by half. Always keep a defogging spray in your car; a $10 bottle lasts weeks when applied weekly, and pre-treating the night before rainy days saves hassle.
