Should I Turn Off the Internal Air Recirculation When Parking and Turning Off the Engine?

[JaxonLynn]

No need to turn it off. After the car is turned off, the entire air conditioning system will not be powered, so leaving it on won't waste electricity. Principle of External Air Circulation: The external air circulation mode uses a fan to draw outside air into the car, meaning there is airflow between the outside and inside of the vehicle. The air blown by the fan comes from outside, and even if the fan is not turned on, there will still be airflow entering the car while driving, replenishing fresh air inside. Principle of Internal Air Recirculation: The internal air recirculation mode closes the airflow passage between the inside and outside of the car. Without the fan, there is no airflow circulation. When the fan is on, the air drawn in comes only from inside the car, creating an internal airflow cycle.

[OClayton]

Should you turn off the internal circulation before parking and turning off the engine? I have to say, it's best to turn it off. Over the years of driving, I've learned this lesson. The internal circulation mode of the air conditioning reuses the air inside the car. If it's left on while parked, the lack of airflow can lead to mold or bad odors, especially during hot summer days or rainy weather when the humid air can cause bacteria to grow in the air conditioning ducts, making it unpleasant when you drive. Once, I forgot to turn off the internal circulation when parking in the garage, and the next day, a foul smell came out when I turned on the air conditioning, costing me unnecessary money for a repair shop visit. Switching from internal to external circulation allows fresh outside air to come in, helping to dry the system and prevent these issues. In the long run, this can also protect the air conditioning components, reduce the load during startup, and indirectly save fuel. However, if the parking environment is polluted or hazy, it's okay to turn on the internal circulation to protect your breathing safety, but remember to check before turning off the engine. Overall, it's recommended to develop the habit of turning it off when parking—a simple action to ensure fresh air inside the car and system health. Safety is no small matter, especially when parking at night.

[Wyatt]

Turning off the air recirculation before parking and shutting down the engine is essential. As an advocate for a healthy lifestyle, I prioritize in-car air quality. Keeping the recirculation mode on for too long recycles carbon dioxide and moisture inside the vehicle, leading to stale air that may cause headaches or allergies when inhaled over time. If left on while the engine is off, the system remains sealed without fresh airflow, allowing moisture to linger and promoting mold growth and bacterial proliferation. For example, parking for several hours in a hot city often results in a stuffy and unpleasant odor upon re-entering the car, significantly impacting health. Switching to fresh air mode before shutting down allows the AC fan to expel residual moisture, maintaining air freshness. From my experience, turning off recirculation noticeably reduces AC odors and boosts alertness. Additionally, in garages or areas with exhaust hazards, keeping recirculation on may trap more pollutants—turning it off is safer. Adopting this habit takes mere seconds but preserves the cabin environment and lowers maintenance costs. Small health-conscious actions yield substantial benefits.

[Gavin]

When parking and turning off the engine, it's recommended to switch off the air recirculation mode. As a tech enthusiast, let me briefly explain the principle: The car's air conditioning in recirculation mode repeatedly cycles the same air. Turning it off when parked prevents moisture buildup in the ducts. Moisture leads to mold growth, which causes unpleasant odors when you next start the car and increases power consumption. Switching it off allows the fan to automatically expel moisture, keeping the system dry and extending its lifespan. The operation is simple - just switch to fresh air mode before turning off the engine.