How to Deal with Fog on the Outside of Car Windows When Using Air Conditioning?
2 Answers
When fog forms on car windows due to air conditioning, solutions include opening windows for convection, using the air conditioning system to defog, or applying defogging agents. Window Convection: If the fog inside the car is not severe, slightly opening the windows on both sides can create airflow between the inside and outside of the car, reducing the temperature difference and gradually dissipating the fog. This method works similarly to using cold air from the air conditioning but without increasing fuel consumption. However, window convection has obvious drawbacks: it is not suitable during rain, snow, or on highways, especially when the fog is heavy, and it can lower the temperature inside the car. Air Conditioning System: Using the air conditioning system to defog is the most common method. Almost all cars today have air vents located under the front windshield. Simply adjusting the air conditioning to the appropriate setting can direct airflow to clear the fog. Cold air can be used for quick defogging when in a hurry, but warm air is generally recommended for most situations. Turning on the fan and the cooling switch will quickly eliminate fog on the windshield, but the downside is that passengers 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 about ten days. Prices range from a few dollars to over a hundred. Alternatively, you can make a homemade solution by mixing dish soap with water at a ratio of 1:10. Apply it to the inside of the front and rear windshields with a clean, soft cloth or use a small spray bottle for application.
I always find it annoying when the car windows fog up, especially on rainy days. Actually, this is mainly due to the significant temperature difference between the inside and outside of the car, just like how water droplets form on the outside of an ice-cold soda can. My usual approach is to turn on the air conditioning right after getting in the car, set it to external circulation, and increase the fan speed to blow air onto the windshield—the fog clears up almost immediately. If I'm in a hurry, I also turn on the rearview mirror heating function, which works especially fast. Remember not to use the wipers to clear the fog; it just comes back right after you wipe it off. If it's cold outside, I simply turn up the air conditioning temperature a bit. Although it uses a bit more fuel, clear visibility is the most important thing. Recently, I asked the car wash attendant to apply an anti-fog treatment to the windows while washing the car, and it really seems to delay the fogging.
