Should the Car's Air Conditioning Use Internal or External Circulation?

3 Answers
CarterLee
07/28/25 6:16pm
Whether to use internal or external circulation in a car's air conditioning system cannot be generalized and should be determined based on the specific situation. The choice between internal and external circulation should be adjusted according to actual conditions. Below is a detailed explanation of both modes: 1. Internal Circulation: Prolonged use of internal circulation can lead to a decline in air quality inside the car because no fresh air is being introduced. However, when the air conditioning is first turned on, internal circulation can cool the interior temperature more quickly. Using internal circulation during summer for cooling is more energy-efficient. However, prolonged use of internal circulation is not advisable, and it's recommended to occasionally open the windows to let in fresh air before closing them and continuing with internal circulation. 2. External Circulation: External circulation continuously brings in fresh air, but in situations like city traffic jams, it may draw in more exhaust fumes. It is advisable to use external circulation more often when heating the car in winter.
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DeVera
08/11/25 10:15pm
I always encounter air conditioning issues when driving to work on hot days. I found that turning on the recirculation mode (where the air inside the car circulates itself) first when using the AC helps cool down the temperature quickly and prevents hot outside air from making the car even hotter. Once the temperature stabilizes and becomes comfortable, I switch to the fresh air mode to let in outside air, preventing the car from feeling stuffy. Prolonged use of recirculation can make people feel dizzy and sluggish—I once forgot to switch on the highway and almost dozed off, which was quite dangerous. In areas with heavy pollution during parking or traffic jams, I use recirculation to block out odors. Simply put, start with recirculation, switch to fresh air once stable, and drive with peace of mind.
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LeKing
09/30/25 3:29am
As someone with years of driving experience, I emphasize that using the air conditioner shouldn't rely solely on recirculation mode. While it cools quickly and filters external dust, poor air circulation can lead to oxygen deprivation inside the car, increasing the risk of fatigue driving. I often use the air conditioner in fresh air mode to maintain air freshness, especially during long drives to prevent CO2 buildup. In summer, the hot air discharge can also help defogging. Occasionally, I switch to recirculation in tunnels or industrial areas to block dust. Remember, combining AC with wipers or ventilation windows yields better results.
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