Does the car air conditioning only work when the car is running?

2 Answers
EllieLee
07/24/25 3:01am
Car air conditioning can only be used when the car is running. Here is an extended introduction: Car air conditioning operation: The cold air compressor of the car air conditioning system relies on the engine's operation to function, and the energy for warm air (hot water) is generated only when the engine is heated. If you turn on the air conditioning when the car is only powered on but not started, it will not produce any cooling or heating effects. Instead, it will rapidly drain the car's battery, ultimately damaging it. Function of car air conditioning: The car air conditioning system is designed to adjust and control the temperature, humidity, air cleanliness, and airflow inside the car cabin to an optimal state, providing a comfortable environment for passengers and reducing travel fatigue. It also creates good working conditions for the driver and plays a crucial role in ensuring safe driving. Generally, it includes a cooling device, heating device, and ventilation system. This integrated system makes full use of the limited space inside the car, has a simple structure, and is easy to operate, making it a popular modern car air conditioning system internationally.
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StSophie
08/10/25 10:34pm
I often rest in my car and noticed that the air conditioning in fuel-powered vehicles only works properly when the engine is running. Once, while waiting for someone, I tried to turn on the AC without starting the engine—only the fan was blowing air, and the compressor wasn't working at all. That's when I realized the compressor can't operate without the engine turning the belt. However, if the engine is still warm after turning it off, the heating system can continue to provide warm air for a while since it uses residual heat from the radiator. The most frustrating part is that electric vehicle owners have it much better—their compressors run independently powered by the traction battery, allowing them to enjoy cool air even while parked and scrolling through their phones for half an hour. For fuel-powered car owners who need temporary AC, it's recommended to idle the engine before turning on the cooling to protect the battery and achieve faster cooling.
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