Should the car air conditioning use internal or external circulation?

[McKiara]

Whether to use internal or external circulation for car air conditioning depends on the situation. Use internal circulation for short-distance driving and external circulation for long-distance driving. Internal and external circulation in cars refer to: 1. Internal circulation means the air conditioning system is closed to outside air and only uses the air inside the car for circulation; 2. External circulation means the car air conditioning system is open to outside air, drawing in external air for circulation. Car air conditioning generally includes cooling devices, heating devices, and ventilation devices. This combined system makes full use of the limited space inside the car, has a simple structure, and is easy to operate, making it the internationally popular modern car air conditioning system.