What does the internal and external circulation of a car mean?
3 Answers
Car air conditioning internal circulation: Internal circulation is like the air in a sealed container, which is extracted, processed, and then sent back into the container. Since the air intake for internal circulation is inside the car, the air conditioning system only circulates the air inside the vehicle, preventing outside air from entering and inside air from escaping. Correct methods for using internal and external circulation: 1. During traffic jams: Use internal circulation for the air conditioning, as external circulation would draw exhaust fumes from outside into the car. 2. General air conditioning cooling: Use internal circulation to quickly lower the temperature inside the car. Once the temperature stabilizes, switch to external circulation appropriately to exchange air with the outside. 3. Air conditioning cooling after outdoor exposure: First use external circulation and open the windows to speed up heat dissipation. After a few minutes, close the windows, switch to internal circulation, and turn on the cooling. 4. Air conditioning heating: Do not rush to turn on the air conditioning when starting a cold engine. Wait for the engine temperature to rise before turning on the heater with internal circulation. Once the temperature stabilizes, switch to external circulation appropriately to exchange air with the outside. 5. Rainy or foggy days: These conditions can easily cause window fogging. To prevent this, simply press the front window defogging button on the air conditioning, lower the temperature slightly, and increase the fan speed.
I often use the recirculation and fresh air modes when driving to and from work. Recirculation mode means the car's air conditioning system only circulates the air inside the vehicle without drawing in fresh air from outside. It's particularly suitable for use during traffic jams or hazy days, as it helps avoid inhaling dust, exhaust fumes, and polluted air, keeping the interior clean. On the contrary, fresh air mode introduces outside air into the car, which is ideal for long-distance driving or when air quality is good, preventing stuffiness and fatigue. I've noticed that cars with automatic air conditioning intelligently switch between these two modes—activating fresh air mode for ventilation on highways and automatically switching to recirculation in congested areas to protect respiratory health. For safety, I manually adjust based on road conditions, such as always switching to recirculation when passing through tunnels to prevent exhaust fumes.
As a car enthusiast, I must highlight the key points about air recirculation: pressing the recirculation button closes the air intake, using only the air inside the car; the fresh air mode does the opposite by opening the intake to bring in outside air. This design is environmentally friendly because recirculation is energy-efficient, consumes less fuel, cools faster in summer, and maintains stable warm air in winter. However, prolonged use may lead to stale air. I recommend using recirculation in urban areas to reduce pollution intake and switching to fresh air on highways to prevent drowsiness. Modern automatic air conditioning systems can even monitor PM2.5 levels and switch modes automatically, enhancing driving comfort. In short, flexible use optimizes both the cabin environment and driving experience.
