Is It Safe to Sleep in a Parked Car with the Air Conditioning On in Summer?

[LeRonan]

It is not safe. Running the air conditioning for a long time while the car is parked poses significant risks to human health. The air circulation inside the car becomes abnormal, and closing the windows can lead to a comfortable environment where one may unknowingly fall asleep, resulting in carbon monoxide poisoning and oxygen deprivation. Idling refers to the engine running without any load, merely overcoming the internal friction resistance of its components without delivering power externally. Sleeping in a parked car with the air conditioning on, even in external circulation mode, is unsafe: 1. In a closed car: The air conditioning produces a large amount of carbon monoxide, which can exceed safe levels within just 20 minutes, causing noticeable suffocation. 2. Regardless of the car type: Whether set to internal or external circulation, carbon monoxide can still enter the cabin. 3. Sealing performance: Even cars with excellent sealing performance are unsafe when the air conditioning is on in internal circulation mode, so it is not advisable to sleep in a car with the air conditioning running.