Which is More Fuel-Efficient: Car Air Conditioner's Internal or External Circulation?
2 Answers
Between the internal and external circulation of a car's air conditioner, the internal circulation is more fuel-efficient than the external circulation, but the difference in actual usage is minimal. Below are the related introductions to the internal and external circulation of a car's air conditioner: External Circulation: External 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 car. However, if the outside weather is extremely dry and hot, using external circulation will require the air conditioning compressor to work continuously to cool the hot air from outside, which consumes a certain amount of fuel. Internal Circulation: Internal circulation involves the recirculation of air inside the car. The air conditioner 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 disengages, reducing the engine load. Therefore, the faster the interior temperature reaches the set value, the sooner the engine load is reduced, leading to a decrease in fuel consumption.
As an economical driver with years of experience, I find that the recirculation mode is generally more fuel-efficient. It reuses the already conditioned air inside the car, eliminating the need to cool down the hot outside air each time. This means the air conditioning compressor doesn't have to work as hard, reducing engine load and naturally lowering fuel consumption. During summer traffic jams in the city, I always switch to recirculation mode, and it feels like the fuel tank drinks less—saving about half a liter per 100 kilometers. Of course, when external air pollution is high, recirculation also protects me from inhaling exhaust fumes. However, in winter or rainy days, I switch back to fresh air mode to defog the windows, as blurred vision is dangerous. Overall, fuel efficiency isn't the only consideration—safety and comfort matter too. But in daily driving, making a habit of using recirculation can genuinely save some money.
