Can You Keep the Air Conditioning On While Parked?

[Norma]

You should not keep the air conditioning on while parked. Carbon Monoxide: When the car's engine is running, incomplete combustion of gasoline in the cylinders can produce high concentrations of carbon monoxide. While driving, the air flow generated by the air conditioning system creates convection, keeping the carbon monoxide concentration inside the car low. Causes Poisoning: However, when the car is parked with the air conditioning still on and the windows and doors are closed, the air inside cannot circulate. If carbon monoxide from the engine leaks into the car, it can gradually accumulate, increasing its concentration and leading to poisoning or even death. Garage Sealing: When using the air conditioning, if you park the car in a garage and take a nap with the air conditioning on, even with the windows open, it can still be dangerous. This is because a garage is a relatively sealed environment, and high concentrations of carbon monoxide can still occur, leading to carbon monoxide poisoning.

[HectorRose]

Be really careful about leaving the air conditioning on while parked, especially during hot and stuffy summers. If the engine is off but the air conditioning is still running, it will drain the battery rapidly. I've experienced this myself—once, while waiting for a friend on the roadside for half an hour with the AC on, the battery died, and the car wouldn't start. It was really embarrassing. Even if the engine is running while the AC is on, it burns fuel idly, wasting gasoline and emitting exhaust that pollutes the air. On top of that, in enclosed spaces like garages or underground parking lots, there's a high risk of carbon monoxide poisoning. Just last year, there was news about someone getting injured because of this. So, I recommend not leaving the air conditioning on continuously while parked. If you must use it, limit it to a few minutes to cool down, then turn it off and open the windows for ventilation or find a shady spot to rest. This way, you stay safe and protect your car's condition.

[Danielle]

From an environmental perspective, I think the habit of idling with the air conditioning on should be changed. When a car is parked with the engine running and the air conditioning on, it continuously burns fuel, releasing large amounts of carbon dioxide and pollutants, which worsens air pollution and global warming. I've checked the data—idling with the air conditioning on for an hour can consume over a liter of fuel, equivalent to driving several kilometers in daily use. This not only wastes money but also harms the planet. Some cities have even enacted laws to prohibit prolonged idling to reduce pollution sources. For electric vehicles, idling with the air conditioning has a slightly smaller environmental impact, but it's still not ideal for traditional vehicles. I suggest minimizing this practice—for example, turning off the engine and opening the windows slightly for ventilation while parked, or finding shaded areas to stay cool. Contributing to environmental protection in this way can also help extend the lifespan of your car.

[MarcusFitz]

The biggest risk of running the air conditioning while parked is health and safety. If the car is parked in an enclosed space like a garage with the engine running and the air conditioning on, carbon monoxide from the exhaust can quickly accumulate, leading to dizziness, poisoning, or even fatal consequences. I once heard about a colleague who fell asleep in the car with the air conditioning on and nearly had to be hospitalized. Even in open spaces, prolonged use of the air conditioning affects air circulation inside the vehicle, making dizziness more likely. Therefore, I advocate avoiding using the air conditioning while parked whenever possible. If you need to cool down, crack the windows for ventilation. Protecting yourself is the top priority—don't risk major consequences for minor comforts.