What are the symbols for external and internal air circulation in car air conditioning?

[MacAdalynn]

The internal circulation symbol is a circular arrow inside a car graphic; the external circulation symbol is an arrow pointing from outside the car into the car. Below is some introduction about internal and external circulation: 1. Internal circulation: The purpose of internal circulation is to prevent dust and odors from being drawn into the car through external circulation, so a control system is set up to close the external circulation air duct and block polluted air from outside the car. 2. External circulation: Since the interior of the car forms a relatively sealed environment, people can easily suffer from oxygen deprivation if they stay in this environment for a long time. Therefore, the air conditioning system adds an air duct to draw in fresh air from outside the car, which then passes through the air conditioning evaporator or heater core to blow out cold or warm air respectively.