What is the difference between the internal and external circulation of a car's air conditioning system?
3 Answers
The differences between the internal and external circulation of a car's air conditioning system are: 1. Different circulation methods: Internal circulation refers to the air inside the car being heated or cooled before being sent back into the car; external circulation involves drawing air from outside the car, heating or cooling it, and then sending it into the car, facilitating gas exchange between the inside and outside of the car. 2. Different symbols: The internal circulation icon features a closed car interior with a circulating arrow; the external circulation icon shows an open car with an external air arrow pointing into the car. The purposes of external and internal circulation are: 1. When turning on the air conditioning for cooling or heating, activating internal circulation can quickly lower or raise the temperature inside the car; 2. When the external air environment is poor, turning on internal circulation is advisable.
The car's air conditioning recirculation mode uses the existing air inside the car without drawing in any fresh air from outside, while the fresh air mode does the opposite by continuously introducing outside air. Having driven for over a decade, I quickly switch to recirculation during heat waves—the car cools down instantly, and it keeps out dust or roadside odors. However, prolonged use can feel stuffy, so I usually switch to fresh air mode after 30 minutes to ventilate and prevent CO2 buildup, which can cause fatigue. On rainy or humid days, fresh air mode is great for defogging—the windows clear up fast. The key difference is the air source: recirculation is convenient but may feel stale, while fresh air mode is more comfortable but can be affected by external pollution. I recommend switching flexibly based on road conditions to ensure safe driving.
I always pay attention to the air quality in the car, especially when traveling with children. The air conditioning's recirculation mode recycles the internal air in a closed loop, while the fresh air mode continuously draws in external fresh air. On routes with clean air, I try to use the fresh air mode to maintain comfortable breathing; but in congested urban areas or during pollen season, I immediately switch to recirculation mode to reduce the intake of pollutants or allergens. On cold and humid days, the fresh air mode is super effective at preventing window fogging, improving visibility and safety; on hot midday, using recirculation mode cools the car faster, but don't use it for too long to avoid feeling stuffy. The core difference lies in the switching between internal and external air sources. Using them properly can enhance family comfort and maintain the air conditioning system. I always clean the filters regularly to ensure the mode switching works effectively.
