What is the difference between internal and external air circulation in a car?
2 Answers
The difference between internal and external air circulation in a car: Internal circulation means the air inside the car is heated or cooled and then recirculated within the car; external circulation means air from outside the car is heated or cooled and then brought into the car, allowing gas exchange between the inside and outside of the car. Specific details are as follows: 1. Internal circulation keeps the air inside the car circulating in a closed loop, represented by an icon of a closed car interior with a circular arrow; external circulation brings outside air into the car, represented by an icon of an open car with an external air arrow pointing into the car. 2. Whether using the heater or air conditioner, start with internal circulation. Although the temperature inside the car will drop, the carbon dioxide exhaled by passengers will increase. Therefore, it's best to switch to external circulation every hour to refresh the air. 3. When turning on the air conditioner for cooling or heating, first activate internal circulation to quickly lower or raise the temperature inside the car. Once the temperature stabilizes, switch to external circulation to exchange air with the outside. 4. If the outside air quality is poor, such as in heavy traffic with high exhaust emissions or in a poorly ventilated underground garage, avoid using external circulation. When driving on the highway, do not open the windows; simply use external circulation.
The most fundamental difference between recirculation and fresh air modes lies in the air source. Recirculation recycles the existing air inside the car, equivalent to breathing with windows closed; while fresh air mode introduces outside air, like opening windows for ventilation. I flexibly switch between them during my daily commute: using recirculation for rapid cooling when first entering the car in summer, then switching to fresh air mode for ventilation after temperature drops; activating recirculation in traffic jams to block exhaust fumes and dust; employing fresh air mode during highway trips to maintain airflow and prevent drowsiness. Fresh air mode works better against window fogging on rainy days as it reduces temperature differences. Remember to regularly replace the cabin air filter - otherwise, fresh air mode may introduce dust and affect health.
