Does Running the AC While Parked Damage the Car?
3 Answers
Running the AC while parked does not damage the car. Here are the relevant explanations: 1. Compressor: Turning on the AC can mean using either the heater or the cooler. When the cooler is activated, the air conditioning system's compressor needs to work. Typically, the compressor is driven by the engine, except in hybrid or fully electric vehicles where it is electrically powered (this discussion excludes purely electric compressors). When the engine is idling, it runs regardless of whether the AC is on or off. However, when the AC is turned on, the engine speed may increase by about 250 RPM. If the vehicle has a variable displacement AC compressor, the change in engine speed might be barely noticeable. Therefore, since the engine runs at idle whether the AC is on or off, using the AC does not harm the car. 2. Air Circulation: Although running the AC does not damage the car, it is important to activate the external air circulation mode and open the windows when idling with the AC on, especially in poorly ventilated areas like underground parking lots. This prevents poor air circulation inside the car, which could lead to carbon monoxide poisoning or suffocation. If the AC is set to heater mode, the compressor is not involved because the heater uses the heat from the engine's coolant, which flows into the heater core. The blower then blows air over the heater core to produce warm air, eliminating the need for the compressor to work. Thus, when using the heater, there is no concern about engine idling damaging the car, as the engine is the only component in operation.
Leaving the air conditioning on while parked can indeed harm your car. The main issues are battery drain and damage. If you turn off the engine but keep the AC running, the battery alone powers the system, which can lead to a dead battery over time, making it difficult to start the car later. Deep discharging the battery shortens its lifespan—I've seen many such cases. The compressor running continuously may also overheat, affecting component performance. However, short-term use has minimal impact, such as when waiting for someone or taking a break. It's advisable to limit this to under 30 minutes and preferably start the engine to let the alternator supply power. In very hot weather, opening windows for ventilation is safer, or check the battery's condition to avoid sudden failures. Prolonged use of AC while parked can also cause interior odors, requiring air filter cleaning. Overall, cautious use helps protect your vehicle.
Using the air conditioner while parked poses risks, and I'm particularly concerned about safety. In enclosed spaces like garages, running the engine produces carbon monoxide—a colorless, odorless gas that can lead to dangerous or even fatal poisoning. Similar accidents have been reported in the news. Even with windows open to ensure airflow, absolute safety cannot be guaranteed. Additionally, draining the battery can easily trap you inside the car. From a health perspective, idling with the air conditioner on also affects air quality, as dust accumulation in the filter may cause respiratory issues. I recommend avoiding this habit whenever possible. If necessary, use the external circulation mode or set a timer to turn off the air conditioner. Safety first, prevention is key.
