What is the difference between the internal and external circulation of a car's air conditioning system?

[VanLeila]

The differences between the internal and external circulation of a car's air conditioning system are: 1. Different circulation methods: Internal circulation refers to the air inside the car being heated or cooled before being sent back into the car; external circulation involves drawing air from outside the car, heating or cooling it, and then sending it into the car, facilitating gas exchange between the inside and outside of the car. 2. Different symbols: The internal circulation icon features a closed car interior with a circulating arrow; the external circulation icon shows an open car with an external air arrow pointing into the car. The purposes of external and internal circulation are: 1. When turning on the air conditioning for cooling or heating, activating internal circulation can quickly lower or raise the temperature inside the car; 2. When the external air environment is poor, turning on internal circulation is advisable.