Should You Use Internal or External Air Circulation for Car AC on Rainy Days?

[SaraLee]

On rainy days, it is more suitable to use external air circulation. If internal circulation is used, the windows may fog up, affecting the driver's visibility. Therefore, it is recommended to use external air circulation and adjust the airflow direction towards the windshield. External circulation helps expel the moisture exhaled by passengers from the car, while the outside cold air is less likely to condense. When the outside air quality is poor or heavily polluted, such as on dusty roads, in congested traffic, or near chemical plants with foul odors or unpleasant smells, internal circulation can be used to prevent bad air from entering the car. If internal circulation is used for an extended period and opening the windows is inconvenient, periodically switch to external circulation to allow fresh air into the car. When there are many passengers in the car, using external circulation helps maintain fresh air and prevents excessive humidity inside the car, which can lead to window fogging.