Why Does Turning on the AC Cause Fogging in Summer?

[Barry]

Fogging on the inside of the windshield in summer is caused by the temperature difference between the inside and outside. Here is an introduction to fogging when turning on the AC in summer: 1. Causes of fogging: When the window temperature is lower than the dew point, the moisture content in the air is insufficient to condense into droplets, so it can only form tiny water particles, which create condensation on the window surface. This is the common fogging phenomenon seen on the windshield. 2. Solutions for fogging: If the fogging is not severe, you can open the side windows slightly to allow air convection inside the car. When the interior temperature approaches the outside temperature, the fog will dissipate. However, this method is only effective when driving at low speeds. If the fog is heavy and opening the windows doesn't help, you can adjust the AC to warm air, increase the temperature, and direct the airflow entirely toward the windshield. The fog will disappear shortly, with a very noticeable effect.