Should You Use Internal or External Air Circulation When Turning on the Heater?

[EliDella]

Whether to use internal or external air circulation when turning on the heater depends on the situation: use internal circulation for short trips and external circulation for long trips. Internal and external air circulation in a car refer to: 1. Internal circulation means the air conditioning system is closed to outside air, only recirculating the air inside the car; 2. External circulation means the car's air conditioning system is open to outside air, drawing in fresh air from outside the car. The functions of a car's air conditioning system are: 1. To cool, heat, ventilate, and purify the air inside the car; 2. To provide a comfortable environment for passengers, reduce driver fatigue, and improve driving safety.