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

[Minnie]

Difference between internal and external air circulation in cars: 1. Air intake method differs: Internal circulation draws air from inside the vehicle, creating airflow circulation within the cabin; External circulation draws air from outside the vehicle, directs it through the air conditioning system for heating or cooling, then blows it out through the vents. 2. Functions differ: Internal circulation primarily serves to promptly and effectively block external dust and harmful gases from entering the cabin; External circulation replenishes fresh air to improve cabin air quality. Automotive air conditioning refers to the climate control system installed in vehicles, capable of cooling, heating, ventilating, and purifying cabin air. It provides passengers with a comfortable environment, reduces driver fatigue, and enhances driving safety.