What is the difference between the internal and external air circulation in a vehicle?

[ElisaLynn]

The differences between the internal and external air circulation in a vehicle are: 1. Different air circulation methods: Internal circulation draws air from inside the vehicle; external circulation draws air from outside the vehicle, which is then cooled or heated by the air conditioning system before being blown out through the vents. 2. Different functions: Internal circulation effectively blocks external dust and harmful gases from entering the vehicle, improving the cooling and heating efficiency of the air conditioning; external circulation brings fresh air from outside into the vehicle, maintaining air quality inside. Internal circulation mode closes the airflow channel between the inside and outside of the vehicle, creating an internal airflow loop that effectively prevents external dust and harmful gases from entering while maintaining the internal temperature. External circulation mode uses a fan to draw outside air into the vehicle, and even without the fan, airflow will still enter the vehicle while driving, replenishing fresh air inside.