When to Use the Car's Internal and External Air Circulation?

[MacCharlie]

Internal air circulation means only the air inside the vehicle is recirculated, while external air circulation allows fresh air from outside to enter the vehicle. Below is a detailed introduction: 1. Introduction: Internal circulation recirculates the air inside the car, driven by the blower. External circulation connects the interior with the outside air. The internal circulation symbol displayed on the screen indicates the car is currently in internal circulation mode. Pressing the internal circulation button again while it is active will turn it off, switching the car to external circulation mode. 2. Applicable Scenarios: Use internal circulation during traffic jams; switch to external circulation for long highway drives.

[SanMiguel]

I think the car's air conditioning recirculation and fresh air modes should be properly switched according to different situations. When driving in the city during traffic jams with poor air quality, turning on recirculation mode can reduce inhaling vehicle exhaust and PM2.5, protecting your health. On highways or national roads, if there are factories or unpleasant odors by the roadside, I usually switch to fresh air mode to let in clean air and prevent dizziness. In hot weather, I first activate recirculation mode when starting the AC to cool down quickly, then switch to fresh air mode after it gets cooler to balance the temperature - this saves energy while keeping comfortable. During rainy days when windows tend to fog up, using fresh air mode prevents window blurring and ensures clear visibility of road conditions. In summary, flexibly switching between modes can both save fuel and enhance driving safety.

[DiPreston]

From my experience, using the air recirculation system properly can prevent health risks. For example, in areas with poor air quality, such as during haze or near chemical plants, I turn on the air recirculation to avoid inhaling dust and harmful gases, reducing allergies and coughing. If there are passengers smoking or food odors inside the car, I switch to fresh air mode to ventilate and restore freshness. During long-distance highway driving, prolonged use of air recirculation can cause stuffiness, hypoxia, and drowsiness, so I switch to fresh air mode every half hour for some fresh air. When entering tunnels or underground parking lots, I immediately turn on air recirculation to block exhaust fumes. This simple but crucial habit can make your driving experience safer and healthier.

[CatherineFitz]

Using the air recirculation mode saves fuel and is eco-friendly. On cold days, start the car with recirculation to warm up faster without wasting heat; on hot days, use recirculation first for quick cooling, then switch to fresh air to maintain temperature, reducing AC load and fuel consumption. For short city drives, use recirculation more to minimize external pollution; on long highway trips, use fresh air for smoother airflow and less engine strain. Occasionally switch to fresh air when air quality is good to bring in fresh oxygen and lower CO2 levels inside. Proper switching also reduces AC wear and extends its lifespan.

[DeWillow]

From a safe driving perspective, switching between internal and external air circulation must be done with attention to scenarios. On rainy days or in winter when humidity inside the car is high and prone to fogging, I always use external circulation to maintain airflow and ensure clear visibility. In traffic jams or high-pollution areas, switch to internal circulation to prevent toxic fumes from entering and avoid distractions. Before entering tunnels or underpasses, activate internal circulation to block exhaust fumes; switch back to external circulation afterward for fresh air. In case of sudden foul odors like dead animal smells, quickly isolate them by switching to internal circulation. On long highway drives, prolonged use of internal circulation may cause chest tightness—switch to external circulation to stay alert and focused. Remember these tips to prevent minor risks.

[SanCorbin]

The use of internal and external air circulation should vary depending on the situation. I often use external circulation during highway cruising to save fuel; in the city during a sandstorm, I immediately switch to internal circulation to avoid dust. During cold starts in winter, internal circulation helps warm up the car faster; after summer exposure, internal circulation cools down quickly, but external circulation is needed to introduce fresh air and prevent odors. Before entering a long tunnel, switch to internal circulation to avoid exhaust poisoning; after exiting, switch back to external circulation for fresh air and comfort. On rainy days, use external circulation to prevent fogging and ensure clear visibility. In short, flexibly control it based on road and weather conditions for a more efficient and relaxed driving experience.