Use Internal or External Air Circulation in Summer?
2 Answers
In summer, start with external air circulation before switching to internal. After entering the vehicle, first activate external circulation to ventilate and dissipate heat, while simultaneously opening windows and sunroof to accelerate cooling. After 3 to 5 minutes when the cabin temperature stabilizes, close all windows, turn on the AC, and switch to internal circulation. When a car has been exposed to summer sun, it accumulates not just heat but potentially various odors - this is when external circulation should be initially used along with fans and open windows for cooling and odor removal. For short urban drives in summer, internal circulation suffices, but during highway driving, alternate between internal and external circulation to ensure safe operation.
In summer, when driving with the air conditioning on, I would first recommend using the recirculation mode for faster cooling. When you first get into the car, it feels like an oven. Using recirculation means the AC only has to cool the air inside the car, rather than battling the hot air outside, so the car cools down within minutes. This also reduces electricity and fuel consumption, making it ideal for eco-conscious drivers. However, don’t keep it on all the time, as the air circulating repeatedly can lead to a buildup of carbon dioxide. After about half an hour, switch to fresh air mode to ventilate and avoid feeling dizzy or lightheaded. During peak hours in the city, when vehicle exhaust is heavy, using fresh air mode can draw in more pollutants, so I try to use recirculation more often to avoid pollution sources. On rainy or humid days, alternate between modes to prevent fogging on the windows, which can obstruct visibility. In short, switching flexibly is the most cost-effective approach—quick cooling without compromising health or spending extra.
