Should the car's air conditioning use internal or external circulation when cooling?

[VanBrody]

When using the car's air conditioning for cooling, it is best to use the internal circulation mode. Using internal circulation in summer is more fuel-efficient and provides the best cooling effect. However, it should not be used for extended periods as this prevents air circulation inside the car. To achieve maximum air conditioning cooling efficiency, internal circulation should be used in summer. More information about car air conditioning is as follows: 1. Internal and external circulation: Internal circulation means the air inside the vehicle is recirculated, meaning the air coming out of the vents is from inside the cabin, and the cabin is sealed off from the outside atmosphere. External circulation means outside air is drawn into the cabin, so the air from the vents comes from outside, and the cabin is open to the atmosphere, not sealed. 2. Advantages and disadvantages: Internal circulation means the air blown by the blower circulates inside the car, with no outside air involved, offering advantages like fuel efficiency and faster cooling (or heating), but the disadvantage is poor air renewal inside the car. External circulation means the blower draws fresh air from outside into the car, ensuring better air quality inside, but cooling (or heating) is slightly slower and less fuel-efficient. Car owners should regularly clean and maintain the air conditioning system to ensure a fresh air environment inside the car.

[DiJulianna]

When driving in hot weather and turning on the AC, I always switch to recirculation mode first to cool down quickly by circulating only the air inside the car, which significantly improves cooling efficiency. After a few minutes when the temperature drops, if the air starts to feel stuffy or the windows begin to fog up, I switch to fresh air mode to bring in outside air. Alternating between these modes helps prevent odor buildup or driver fatigue caused by prolonged recirculation, especially during long drives—I frequently do this to ensure the cabin stays comfortable. On highways, I’ve tried using fresh air mode to save some fuel, as it might reduce engine load, but it depends on road conditions—for example, in city traffic, fresh air mode can draw in more exhaust fumes. For regular car maintenance, I make it a habit to check and clean the cabin air filter periodically, as keeping it clean ensures both modes work efficiently. The key is to switch flexibly—don’t just stick to one mode all the time.

[CorbinAnn]

As a long-time driving enthusiast, I focus on how to save fuel and money with the air conditioning system. When cooling down with the AC, I first activate the recirculation mode to quickly cool the cabin and reduce energy consumption. However, keeping recirculation on for too long can increase compressor load and become less economical, so once the temperature stabilizes, I often switch to fresh air mode to introduce outside air and reduce overall strain. In hot weather, fresh air mode also prevents window fogging, improving visibility and safety. However, in polluted areas or during pollen season, I prioritize recirculation to avoid unpleasant odors. Developing this habit not only extends the AC's lifespan but also helps control fuel consumption. Making small adjustments based on season and road conditions is practical—for example, using fresh air mode on long summer drives balances air freshness with energy efficiency.

[RhettDella]

When I turn on the AC, I usually start with the recirculation mode to cool down the car quickly, then switch to fresh air mode to replenish oxygen and prevent stuffiness or dizziness—especially when children are onboard. For short trips, simple recirculation suffices, but on long drives, I manually toggle between modes more frequently to ensure proper airflow. During daily driving, I adjust based on weather humidity levels, using fresh air mode to defog and maintain a refreshing cabin.