How to open the No.4 x8 outer ring?

The opening method of automobile external circulation is as follows:

Directly press the external circulation button on the central control panel to open it. The key sign of external circulation is the arrow pointing from the outside of the front windshield of the vehicle to the inside of the vehicle.

The working principle of external circulation is: the fan sucks the outside air into the car and blows it out of the car through the fan, thus achieving the effect of ventilation without opening the window. The methods of circulating air in automobiles are: 1, internal circulation in traffic jams and external circulation in high-speed driving; 2. Internal and external circulation should be combined with air conditioning and warm air; 3. When driving for a long distance, external circulation can make fresh air outside the car enter the car to avoid low oxygen content in the car.