Should the internal or external circulation be used when turning on the cold air?

[AmaraAnn]

When turning on the cold air in a car, the external circulation should be used. The air conditioning system has two circulation modes: internal and external. Here is relevant information about internal and external circulation: 1. Internal circulation means the air inside the vehicle is recirculated, i.e., the air coming out of the vents is from inside the cabin, which is sealed and not connected to the outside atmosphere. External circulation means outside air enters the cabin, so the air from the vents comes from outside the vehicle, and the cabin is not sealed, being connected to the outside atmosphere. 2. Internal circulation refers to the air blown by the fan circulating only inside the vehicle. Since no outside air is involved, it has the advantages of saving fuel and cooling (or heating) quickly, but the disadvantage is that it does not facilitate air renewal inside the vehicle. External circulation means the fan draws fresh air from outside into the vehicle, which ensures better air quality inside the cabin but cools (or heats) slightly slower and consumes more fuel.