How to use the internal and external circulation of the car correctly?

First, after the car is exposed to the sun in summer, we must turn on the external circulation first when we get in the car, so that the formaldehyde and other harmful gases in the car can be quickly discharged, and then turn on the internal circulation after 10 minutes, so that the effect is the fastest.
 
Second, when someone smokes in the car, you must turn on the external circulation, so that the smoke in the car can be discharged quickly.

Third, when there is a traffic jam, you must turn on the internal circulation, so that the exhaust gas outside the car will not enter the car.
 
Fourth, turn on the air conditioner on rainy days, turn on the AC and turn on the external circulation, and at the same time turn on this fan-shaped icon, so that the glass will never fog up again.

Fifth, when you turn on the air conditioner in the summer, you must turn on the internal circulation, so that the cold air in the car cannot go out and the hot air outside the car cannot come in, and the cooling effect is excellent.
 
Sixth, when you turn on the air conditioner in the winter, you must turn on the external circulation, which not only saves fuel, but also prevents frost on the glass. Finally, when driving on the highway, you must turn on the external circulation, so that the air in the car is always circulating and the driver is not prone to hypoxia.