Which is the external circulation mode between BMW A and M?

[LeBethany]

BMW A mode automatically switches between internal and external circulation. Below are the specific introductions to car internal and external circulation modes: 1. External circulation: This mode draws air from outside the vehicle, directs it through the air conditioning system for heating or cooling, and then blows it out through the vents. Essentially, external circulation introduces fresh air to improve the air quality inside the car. It should be used for defrosting in winter or defogging in summer, as the air drawn from outside contains higher oxygen levels and is drier, making it more effective for these purposes. 2. Internal circulation: This mode recirculates air from inside the vehicle, creating an airflow cycle within the cabin. Its main function is to effectively block external dust and harmful gases from entering. It helps warm up the car faster in winter, cool down more quickly when using air conditioning in summer, and can also be used during smoggy conditions. Internal circulation maintains cabin temperature more efficiently by recirculating the existing air.