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

[OAnderson]

Internal air circulation is symbolized by a closed car interior with a circular arrow; external air circulation is represented by an open car with an air arrow pointing into the vehicle. External circulation mode uses a fan to draw outside air into the car, meaning the air passage between the exterior and interior is open. Even when the fan is off, airflow is still drawn into the car while driving, replenishing fresh air inside. Internal circulation mode closes the airflow passage between the inside and outside of the car. Without the fan, there is no airflow circulation, and when the fan is on, the airflow drawn in comes solely from inside the car, creating internal air circulation. Internal circulation primarily serves to promptly and effectively block external dust and harmful gases from entering the car, such as when driving through areas with smoke, dust, strong odors, or in heavy traffic, preventing harmful exhaust emissions from preceding vehicles.