What is the difference between the internal circulation and external circulation of car air conditioning?

[CollinDella]

Here are the specific differences between the internal circulation and external circulation of car air conditioning: 1. Symbols: The internal circulation symbol is a circular arrow inside a car graphic; the external circulation symbol is an arrow entering the car from outside. 2. Working methods: Internal circulation draws air from inside the car, creating an airflow cycle within the vehicle. Its main function is to effectively prevent external dust and harmful gases from entering the car. External circulation draws air from outside the car, directs it to the air conditioning system for heating or cooling, and then blows it out from the vents. 3. Usage: Internal circulation heats up the car faster in winter and cools it down faster when the air conditioning is on in summer. It can also be used on smoggy days. External circulation is used for defrosting in winter or defogging in summer, as the air drawn from outside is richer in oxygen and drier, making it more effective for defrosting or defogging.