Should the car's cold air use internal or external circulation?

[LeTyler]

Both internal and external circulation modes can be used when the car's cold air is on. Setting the air conditioning to internal circulation mode will quickly raise the temperature inside the car. Once the car feels warm, switching to external circulation helps with air circulation inside the vehicle. The blower draws fresh air from outside into the car, ensuring good air quality inside. Internal circulation means the air inside the vehicle is recirculated; the air coming out of the vents is from inside the cabin, and the cabin is sealed off from the outside atmosphere. External circulation means outside air enters the cabin; the air from the vents comes from outside, and the cabin is not sealed off from the outside atmosphere.