
Correct practice is to alternate between internal and external air circulation in winter. Concepts of internal and external circulation: Internal circulation means the air conditioning system shuts off the flow of outside air and only recirculates the air inside the car. External circulation means the car's air conditioning system opens to draw in outside air for circulation. Advantages of alternating use: The cooling and heating effects of the air conditioning system are faster, preventing excessive carbon dioxide concentration which can lead to decreased oxygen levels inside the car. This is when people are most prone to drowsiness, affecting safe driving. It also keeps the air inside the cabin clean, maintaining a good cabin environment.


