Does the car air conditioning only work when the car is running?
3 Answers
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.
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.
After driving for over a decade, I've realized that traditional fuel-powered vehicles' air conditioning systems rely entirely on engine operation. The compressor is belt-driven during cooling, meaning it stops working when the engine is off—you can only use the fan to circulate ambient air. Once during camping, I tried running just the fan with the engine off and drained the battery completely within two hours. Electric vehicles are entirely different—their AC compressors are powered independently by high-voltage batteries, allowing you to comfortably run the AC while parked. However, it's important to note that all vehicles consume energy when using parking climate control: fuel cars drain the starter battery, while EVs deplete the traction battery. Extended use with the engine off may lead to battery depletion or reduced EV range.
