Is it more fuel-efficient to use the internal or external air circulation?
2 Answers
Using the internal air circulation is more fuel-efficient than the external air circulation. Here are the relevant details: External air circulation: External air circulation refers to drawing air from outside the vehicle, directing it to the air conditioning system for heating or cooling, and then blowing it out through the vents. External circulation can replenish fresh air and improve the air quality inside the vehicle. However, if the weather outside is extremely dry and hot, using external circulation requires the air conditioning compressor to work continuously to cool the hot air from outside, which consumes a certain amount of fuel. Internal air circulation: Internal air circulation involves recirculating the air inside the vehicle. The air conditioning system draws in the interior air, cools it, and then returns it to the cabin. Once the interior temperature drops to the set value, the air conditioning compressor stops working, reducing the engine load. Therefore, the faster the interior temperature reaches the set value, the sooner the engine load is reduced, leading to lower fuel consumption.
Using the car's air conditioning in recirculation mode generally saves more fuel. I discovered this from my own driving experience. During summer traffic jams in high temperatures, turning on the recirculation mode allows the system to circulate air directly from the cabin, eliminating the need to heat or cool outside air, thereby reducing the load on the AC compressor. Since the compressor is driven by the engine, fuel consumption naturally decreases. In winter, recirculation also helps retain warm air inside the cabin. However, prolonged use of recirculation can make the air stuffy, so I often switch to fresh air mode for a few minutes to ventilate. Although fresh air mode introduces outside air, it requires the system to handle external temperature changes, especially in polluted urban areas or during high-speed driving with strong winds, making the AC work harder. Overall, to minimize fuel consumption, I use recirculation more often and switch to fresh air mode only briefly when air quality is good. After adopting this habit, I noticed a slight reduction in fuel costs per 100 kilometers.
