Why Should You Turn Off the Air Conditioner When the Car Is Turned Off?
2 Answers
Turning off the air conditioner when the car is turned off is necessary because the engine can no longer drive the compressor after shutdown, rendering the air conditioner unable to cool. If the air conditioner continues to run after the car is turned off, it will reduce the battery's lifespan. The cooling principle of a car's air conditioner is quite simple: when the AC button is pressed, the compressor clutch engages, allowing the engine to drive the compressor. Additional Information: 1. While running, the compressor continuously compresses the refrigerant and delivers it to the evaporator. 2. The refrigerant absorbs heat and expands inside the evaporator, thereby cooling the evaporator. 3. The cooled evaporator can then cool the air blown by the blower, allowing the air vents to blow cold air. 4. After the engine is turned off, the compressor stops running, and the air conditioner can no longer cool. 5. Immediately after turning off the engine, the air conditioner may still blow cold air because the evaporator remains relatively cold.
I used to be a lazy driver, always thinking it was fine to let the AC turn off automatically after shutting down the engine. But one night, I forgot to turn off the AC, and the next day, my car wouldn't start at all—costing me time and money for a tow truck. Since then, I've developed the good habit of turning off the AC before shutting down the engine. The AC runs on the car battery, and if it's still operating when the engine is off, it drains the battery quickly, leading to a dead battery. Starting the car with the AC on also puts excessive load on the engine, which can damage the starting system—repairs aren't cheap. Additionally, sudden power cuts can harm internal components like the compressor, leading to costly replacements over time. Simply put, this habit protects the car battery, extends its lifespan, reduces unexpected breakdowns, and saves money and hassle. Now, I even teach my friends to do the same—it makes driving much more worry-free.
