Why is there still airflow when the recirculation mode is on?
3 Answers
This situation is quite normal because the recirculation mode cannot completely isolate external air. Recirculation mode: Recirculation mode refers to the closed-loop circulation of interior cabin air, while fresh air mode involves air exchange between the interior and exterior. Use recirculation mode in congested traffic or poor air quality environments. On highways, you should switch to fresh air mode approximately every hour to renew the cabin air and prevent oxygen deprivation. Function of recirculation mode: It allows interior air to circulate in a closed system; the cabin air is reheated or recooled before being redistributed. Generally, whether using heating or cooling, you should first activate recirculation mode. However, prolonged use of recirculation mode will lead to increased carbon dioxide levels from passenger exhalation despite temperature regulation. Therefore, switch to fresh air mode every hour to ventilate the cabin.
As a long-time car maintenance enthusiast, I've encountered several instances where air still leaks in despite having the recirculation mode on. This is usually because the air flap in the AC system is stuck or clogged with dust, preventing it from fully sealing the outside air intake. Sometimes, as the vehicle ages, the door or window seals wear out or deform, allowing cold air to sneak in. I remember one time on the highway when my car's flap motor malfunctioned—even with recirculation on, the wind still seeped in, which was particularly uncomfortable during winter. I recommend first manually checking for obvious obstructions near the vents. If cleaning doesn’t help, it’s best to visit a professional shop for diagnosis, as air duct leaks can also allow external pollutants to enter the cabin, affecting driving safety. Regularly replacing the cabin air filter can help minimize such issues and keep the system running smoothly.
I've discussed this topic with many friends. Even with the recirculation mode on, air still gets in, which often happens with older cars. The reason might be a malfunctioning air vent switch or a faulty sensor in the air circulation system, causing the flap not to close tightly. Once, while driving to the suburbs, I suddenly smelled burning grass outside because the recirculation mode didn't fully isolate the airflow. It's best to check if the indicator light is working properly when operating it; if air leakage is accompanied by noise, it needs to be addressed immediately to avoid increased odors or energy waste in the car. You can try cleaning the air filter yourself, but if there's no improvement, it's better to have a mechanic take a look. Maintaining a sealed cabin environment is crucial for safe driving.
