Should the car's air conditioning use the internal circulation mode?
4 Answers
It depends on the specific situation. Car air conditioning systems generally have both internal and external circulation switches. When using external circulation, the air conditioning draws air from outside the vehicle, while internal circulation recirculates the air inside the car. It's best to alternate between internal and external circulation modes. When the outside air is clean and of good quality, external circulation can be used. Without fresh air from outside, the air inside the vehicle will gradually become stale. On the other hand, when the outside air is polluted, filled with exhaust fumes, or excessively hot, internal circulation should be used. Functions of internal circulation: The purpose of internal circulation is to prevent dust and unpleasant odors from entering the vehicle through external circulation. Therefore, a control system is set up to close the external circulation air ducts, blocking out contaminated air from outside. Functions of external circulation: Since the interior of a car forms a relatively sealed environment, prolonged exposure can lead to oxygen deprivation for occupants. To address this, the air conditioning system includes an additional air duct that draws in fresh air from outside. This air then passes through the air conditioning evaporator or heater core to deliver either cool or warm air, respectively.
I always use the air recirculation mode when turning on the AC, as it cools the car faster by preventing outside heat from entering. In summer, this quickly chills the cabin while saving fuel. It's especially useful for city driving—during traffic jams with exhaust fumes everywhere, recirculation blocks out dust and keeps the air inside fresh. However, you shouldn’t keep it on indefinitely. Prolonged use leads to poor air circulation, CO₂ buildup causing dizziness, and fogged-up windows, particularly on highways or rainy days. Here’s my routine: in scorching summer heat, I run recirculation for 10 minutes for rapid cooling before switching to fresh-air mode. The same applies to winter heating, but with more fresh-air cycles to prevent fogging. The key is adapting to external conditions—use recirculation when outside air is polluted, then switch it off for ventilation when air quality improves. Regular toggling promotes healthier driving, avoiding stuffiness while reducing AC strain.
I think using the air recirculation mode when the AC is on is quite necessary, especially for health reasons. For example, in my family, there's someone with rhinitis. When driving in heavily polluted urban areas, the recirculation mode can filter out some pollen and smoke, preventing people in the car from constantly sneezing or feeling chest tightness. However, recirculation isn't a cure-all. Keeping it on for too long can lead to oxygen deficiency, making drivers prone to fatigue. I once forgot to switch the circulation mode during a long-distance drive and ended up feeling completely drained. My suggestion is to turn off recirculation on outdoor stretches with good weather or when the air is fresh, letting natural airflow into the car for a refreshing and energizing effect. Also, if there are many people in the car or unpleasant odors, manually switch to fresh air mode for quick ventilation. Overall, recirculation is useful in specific environments but shouldn't be relied on exclusively. It's best to adjust flexibly based on road conditions and weather.
I found that using the air conditioning in recirculation mode can help save some fuel costs. When the AC is turned on, less hot air enters the car, making the compressor work more efficiently and reducing fuel consumption. This mode helps me make fewer stops at gas stations during long drives. However, it can actually decrease efficiency when it's cool outside or when driving on highways, as repeatedly cooling and reheating the same air in recirculation mode puts a heavier load on the system. I usually only use recirculation mode during peak high-temperature periods, like for a quick 10-minute cool-down in city traffic jams; the rest of the time, turning it off makes for a smoother ride. Remember to crack the window occasionally for fresh air to keep the cabin from getting stuffy, ensuring safer and more efficient driving.
