What does the internal and external circulation of car air conditioning mean? Why do we need to use an external loop when running on highways?

Many people can start a car when they buy it, but there are many functions in the car that they don't know how to use. Once, someone just picked up a car in the summer, closed the windows,and left the air conditioning on, and got heatstroke. The reason is that the air conditioning is not turned on, only the air volume switch is turned on, and the AC switch is not turned on, resulting in only blowing air without cooling. As we all know, to turn on the AC switch when turning on the air conditioner, there are many other buttons on the air conditioning control panel, including adjusting the air volume, adjusting the temperature, and the internal and external circulation switch. What we are going to talk about today is the issue of internal and external circulation. Many people do not know their functions, let alone when to use them? Should internal circulation or external circulation be used on highways?

When the external air is good, external circulation should be used, and when the external air is not good, internal circulation should be used. External circulation should be used on highways, but internal circulation should not be used continuously as long as driving for a long time. First of all, we need to know what inner and outer circulation means? The air blown out by the air conditioner is sucked in from outside the car, which is called the external circulation, and the air blown out from the air conditioning pipeline sucked in from inside the car is called the internal circulation. That is to say, during internal circulation, the carriage is closed and the air is not exchanged with the outside world. During the external circulation, the carriage is not sealed and air is constantly sucked into the carriage from the outside.

Because driving on highways often involves long-distance trips and longer driving times. If internal circulation is used, due to the sealing of the car, the air cannot be exchanged with the outside world, and the oxygen inside the car is breathed out, the oxygen content will decrease, the carbon dioxide concentration will increase, and the driver will feel stuffy inside the car, leading to faster fatigue. Therefore, it is necessary to use external circulation to constantly allow fresh air to enter the carriage, ensuring that the oxygen content in the car is sufficient and the driver is not easily sleepy. Highways are also built on the outskirts of cities, with less air pollution and more trees around them. The air quality is good, and there is no problem using external circulation.

If the temperature is just right, neither cold nor hot, and there is no need to turn on the air conditioning, then the air conditioning should also be turned on for external circulation, that is, the air conditioning duct should be connected to the outside world. In this way, even if the blower is not turned on, there will still be wind entering the air conditioning duct and blowing out from the air outlet when the vehicle is traveling at a faster speed. The wind blown out is natural and can still keep the air inside the car fresh. Without turning on the blower, it does not consume electricity. It should be noted that the switch for controlling the temperature should not be turned to the warm air position, as this will blow out hot air. It should be turned to the cold air position, with the knob pointing towards the blue part, in order to blow natural air. The automatic air conditioning only needs to lower the temperature.

No one knows which internal and external circulation switch it is, as shown in the above picture. The icon is a small car, and an arrow passes through the car from the outside, indicating that it is an external circulation switch, which means that air enters from the outside. An arrow that only rotates inside the car indicates an internal circulation switch, meaning that air only circulates inside the car. If there is only an internal circulation switch without an external circulation switch on the car, is it impossible to turn on the external circulation? No, as long as the internal circulation switch light is on, it indicates that it is in the internal circulation state. If the internal circulation switch light is not on, it indicates that it is in the external circulation state. Any car has internal and external circulation. The internal and external circulation should not be used as a decoration. It should be used in congested roads, windy and dusty weather, or when the external odor is not good. In most other times, the external circulation can be used.

From：WONDEE Autoparts

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