How Long Can a Car Idle with the AC On?
2 Answers
It is advisable to limit it to about 15 minutes. Prolonged idling can lead to poor heat dissipation and damage to the car engine. Below is an introduction to engine-related content: Energy Conversion: An engine is a machine capable of converting other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (Stirling engines, steam engines, etc.), jet engines, electric motors, etc. For example, an internal combustion engine typically converts chemical energy into mechanical energy. Device: An engine can refer to either a power generation device or the entire machine including the power unit (e.g., gasoline engines, aircraft engines). The engine was first developed in the UK, so the concept of an engine originates from English, with its original meaning referring to "a mechanical device that generates power."
Having worked in car repairs for decades, I've seen countless owners idling their cars with the AC on while waiting, always wondering about the time limit. Mechanically speaking, with the engine running and the AC operating, a car can theoretically last several hours, especially with a full tank—five or six hours is no issue. But running out of fuel and auto-shutdown isn't the only concern. The battery charges at idle but isn’t guaranteed to hold up, especially in older cars with weak batteries, which might die within two hours. There’s also the risk of engine carbon buildup reducing performance. So, if you want practical advice, exceeding an hour starts to get risky, particularly in summer when high temps strain the cooling system, leading to overheating. As a habit, it’s best to turn off the engine if waiting over 30 minutes—saves fuel, keeps the car healthier, and extends its lifespan.
