What does the internal and external air circulation in a car mean?
2 Answers
Car air conditioning internal and external circulation means: 1. Internal circulation allows air to circulate only inside the car, driven by the blower to cycle the air within the vehicle. 2. External circulation connects the inside of the car with the outside. While driving, airflow automatically enters the car using wind pressure, and when stationary, outside air can still enter the blower through the air ducts and be blown into the car. There are two situations when deciding whether to use internal or external circulation in car air conditioning: 1. When the outside air quality is poor, to prevent harmful gases from entering the cabin, it is necessary to set it to internal circulation. 2. During long highway drives, to prevent a decrease in oxygen levels inside the car, it is advisable to alternate between internal and external circulation.
Having driven for over a decade, I use the air recirculation and fresh air modes quite frequently. Simply put, the recirculation mode closes all windows and only circulates the air inside the car, just like turning on the AC with doors and windows shut. I use this mode in traffic jams or when passing by areas with unpleasant odors, as it prevents exhaust fumes or roadside barbecue smells from entering the car. The fresh air mode does the opposite, specifically drawing outside air into the car. I use this mode in suburban areas with good air quality, as it keeps the cabin air flowing and feels particularly refreshing. However, using recirculation for more than 20 minutes can make the cabin feel stuffy—just press the button with an arrow on the dashboard to switch modes. Remember, in winter, if the windows fog up, switching to fresh air mode and blowing for a while will clear the fog quickly.
