Why Does the Windshield Fog Up When Using Air Conditioning in Summer?

[Sousa]

In summer, when the air conditioning is turned on inside the car, the outside temperature is lower than the inside temperature, causing the water vapor inside the car to form many tiny water droplets. The surface of the windshield is not perfectly smooth and has many small imperfections, so these tiny water droplets adhere to the windshield, resulting in fog formation. Below are some methods to deal with fogging on the car windows when using air conditioning in summer: 1. Use the air conditioning system to remove fog: The air conditioning system can be used to remove fog from the glass in both winter and summer. In winter, turning on the cold air conditioning can effectively remove water fog from the glass. However, in summer, it's not practical to turn on the heating for this purpose. The best method is to switch between the internal and external air circulation to allow better airflow, which speeds up the evaporation of the fog. This can quickly remove water fog from the glass. Additionally, periodically switching between internal and external circulation can help purify the air inside the car, making the ride more comfortable. 2. Apply soapy water: You can apply soapy water to the inside and outside of the windshield and then use the wipers to wipe it off once or twice. The soapy water on the inside of the windshield can be gently wiped with a tissue until it is semi-dry. Once the soapy water is completely dry, the windshield will not fog up. As long as it is not wiped off, this method can generally last for about a week.