Why can't Mercedes-Benz keep the air recirculation mode on all the time?

[LaTaylor]

Because keeping the air recirculation mode on for a long time when the air conditioner is turned on will cause the air inside the car to not circulate. It is necessary to appropriately turn on the external circulation to promote air circulation, keep the air inside the car fresh, and avoid air turbidity. The principle of internal circulation is that the air circulates in the closed space inside the car, which causes the oxygen content in the car to continue to decrease. Moreover, if the gasoline in the cylinder does not burn completely, the unburned carbon monoxide from the engine may also leak into the compartment. Therefore, the air quality in the car will become worse and worse. The use of internal and external circulation should be combined with the air conditioner and heating, as well as environmental factors, to make a judgment. Taking the winter inside the car as an example, when the vehicle turns on the air conditioner, it is necessary to turn on the internal circulation and turn off the external circulation, because once the external circulation is turned on, the same situation will be formed inside and outside the car, and there will be a certain degree of air flow between them, which will affect the circulation use of the vehicle, and this circulation is not conducive to the use of the vehicle.