What is the difference between the internal circulation and external circulation of car air conditioning?
2 Answers
Internal circulation means not allowing outside air to enter the car. Due to the limited space inside the car, if the windows are closed and internal circulation is used for a long time, the car will quickly be filled with moisture from human respiration, and the oxygen level will also decrease. External circulation, simply put, is to exhaust the air inside the car to the outside and then draw fresh outside air into the car. Here is an introduction to the selection of car air conditioning modes: 1. Summer: Use internal circulation more often when turning on the air conditioning in summer. 2. Winter: Use external circulation more often when turning on the heater in winter. 3. When air quality is poor: Use internal circulation when the air quality is poor, and use external circulation otherwise.
I've been driving for many years, commuting every day, and the difference between recirculation and fresh air mode is really important. Recirculation mode only circulates the air inside the car without drawing in outside air. This mode is especially suitable for hot summer days or during traffic jams because the AC doesn't need to cool down the hot outside air, making the car cool down quickly while also saving some fuel. However, prolonged use can feel stuffy with stale air. Fresh air mode does the opposite by bringing in outside air for ventilation. It's particularly useful during spring and autumn when the air quality is good, or on rainy days when windows tend to fog up—it clears up quickly, preventing fog from affecting driving visibility. The downside is that it's less efficient on hot days, requiring more AC power. My personal habit is to start with recirculation mode for quick cooling, then switch to fresh air mode after a while to maintain air circulation. Additionally, in heavily polluted urban areas, recirculation mode helps reduce smog entering the car, something I always pay attention to. Overall, using these two modes properly can make driving more comfortable and energy-efficient.
