Should the internal circulation be turned on when using AC in summer?
2 Answers
It is recommended to turn on the internal circulation when using AC in summer. Here are the relevant explanations about using AC: 1. In summer, the car AC only cools the hot air through the compressor and then delivers it into the car; 2. If you turn on the internal circulation while driving, it will further compress and cool the air inside the car to achieve a cooler effect, while the external circulation requires cooling the hot air from outside each time; 3. Since the cooling effect of each circulation cycle is limited, the internal circulation can obviously provide better cooling performance; 4. The advantage of internal circulation is energy efficiency. For example, when the outside temperature is lower than inside, cooling this external air would consume most of the cooling capacity. However, the disadvantage of internal circulation is that it continuously recirculates the same air inside the car, leading to a decline in air quality, which can easily cause driver fatigue. Additionally, as passengers breathe, the humidity inside the car increases, potentially leading to fogging on windows.
Using the recirculation mode with AC in summer is quite effective. I used to do this all the time, especially on scorching days when getting into the car felt like stepping into a steamer—it was unbearable. Hitting the recirculation button right away helps cool down the cabin faster, preventing the AC system from constantly drawing in hot air from outside, which is inefficient and wastes fuel. However, keeping it on for too long can feel stuffy. I usually turn on recirculation for the first few minutes to cool down quickly, then switch back to fresh air mode or crack a window for ventilation to keep the air flowing. After all, the AC is meant for comfort, and letting the air get stale defeats the purpose. Regularly cleaning the AC filter also helps improve air quality. Remember, even on long drives, don’t keep recirculation on continuously—with more passengers, CO₂ levels rise and can affect driving focus.
