What Happens If the Car Is Turned Off Without Turning Off the Air Conditioning?
2 Answers
Leaving the air conditioning on when the car is turned off can affect the engine and battery. If the air conditioning is not turned off before shutting down the car, the air conditioning system will automatically start working the next time the vehicle is started. This places an additional burden on the engine, causing an instant high power load, which over time can lead to engine component wear, increased carbon deposits, and battery drain. When using the car air conditioning, it is advisable to periodically set the air conditioning to the maximum setting for about 10 minutes to effectively prevent dust accumulation. Alternatively, cleaning the air filter during car washing or using an air conditioning cleaner when possible can also be beneficial.
I've been driving for decades and have plenty of experience. The most immediate problem with leaving the AC on when the engine is off is severe battery drain. The blower fan keeps running, relying on the car battery for power. If the car is stationary, the battery will slowly deplete. Especially when parking overnight in summer, you might find the car unable to start the next day, requiring roadside assistance or a jump-start—what a hassle. Over time, this habit drastically shortens battery life, accelerates aging, and leads to unnecessary expenses for replacement. Additionally, the AC may automatically engage during startup, placing extra strain on the engine and affecting component durability. I believe developing good habits is crucial: turn off the AC and other non-essential electronics before exiting the car. This saves hassle, protects your vehicle, and avoids unexpected roadside embarrassments.
