What does the car's internal and external circulation mean?
3 Answers
Car internal circulation refers to the air conditioning system closing the air circulation with the outside, only using the air inside the car to circulate, while car external circulation means the air conditioning system opens to allow air exchange with the outside, drawing in outdoor air for circulation. The functions of the car air conditioning are: 1. Using the continuous phase change cycle of refrigerant to achieve cooling effects; 2. Removing dust, odors, smoke, and toxic gases from the car's interior air to freshen the air and increase the relative humidity inside the car. The maintenance methods for car air conditioning use are: 1. Do not set the temperature too low; 2. Control the direction of the air outlet; 3. Avoid prolonged use; 4. Appropriately turn on high fan speed; 5. Turn off the air conditioning when driving at low speeds.
After driving for more than ten years, I finally figured out the tricks of using the air recirculation and fresh air modes. The recirculation mode keeps the air inside the car circulating, which is perfect for blocking exhaust fumes in traffic jams or maintaining coolness when using the AC in summer. After all, the AC doesn’t have to constantly cool down new hot air coming in, which definitely saves fuel. The fresh air mode draws in outside air, making it especially comfortable on highways or in areas with clean air, like the suburbs. In winter, it can also warm the car directly using the engine’s heat. However, be cautious—using fresh air mode on rainy days can bring in moisture, leading to foggy windows. In such cases, switching to recirculation mode and turning on the AC defogger works faster. Also, using recirculation mode for too long can make the cabin feel stuffy, so remember to switch to fresh air mode every hour for ventilation.
For families with kids like ours, air quality inside the car is a top priority. The recirculation mode can block pollen and smog, which is great for children with allergies. But last time on a long drive, we forgot to switch modes, and our child complained of dizziness—turns out prolonged recirculation caused CO₂ buildup. Here's our routine now: always use recirculation in city traffic to avoid exhaust fumes; switch modes before entering tunnels; use fresh air mode on highways for ventilation; and open fresh air when new car interiors smell. For cars over three years old, change the cabin air filter every six months—otherwise, no circulation mode will work if the filter's clogged. Oh, and smoking in recirculation mode? The smoke will just keep circling around!
