Is it okay to sleep in the car with the air conditioning on and the engine running?
2 Answers
No, it is very dangerous. Prolonged idling can easily produce toxic gases, which are highly likely to enter the car through the air conditioning system, leading to potential poisoning over time. This is especially hazardous in poorly ventilated areas such as underground parking lots or garages. Below is additional information: 1. Turn off the air conditioning before shutting down the engine: It is necessary to turn off the air conditioning before shutting down the engine because if the air conditioning is not turned off, it will automatically start when the engine is next turned on, which unnecessarily increases the engine's load. However, it is important to note that the external circulation should be turned on either before or after shutting down the engine. This is because the evaporator, which has been cooling, will accumulate many small water droplets on its surface after the car is parked. If left unattended, bacteria can grow inside the evaporator over time, leading to a musty smell. 2. Do not stay in the car for too long while idling: When the car is idling, you should not stay inside for too long. The exact duration depends on the environmental and climatic conditions. If there is wind, staying for about 15 minutes is generally safe, but if there is no wind, do not exceed 5 minutes. Car exhaust contains a large amount of toxic gases, especially carbon monoxide, which is present in higher concentrations during idling. Since carbon monoxide is denser, the exhaust emitted from the tailpipe can create a high-concentration zone of carbon monoxide around the car, which can enter the cabin through the air vents and accumulate inside. Therefore, when the car is stationary, whether the air conditioning or heating is on or the engine is idling, it is unsafe to stay inside the car for extended periods, as this poses significant risks.
I think this is quite dangerous. The news recently reported someone suffering from carbon monoxide poisoning after sleeping in a garage. If you must rest in the car, I suggest cracking the windows slightly to maintain airflow. Keeping the engine idling with the AC on for long periods consumes a lot of fuel—a 1.5L engine burns about 2-3 liters per hour. Sleeping overnight like this is equivalent to wasting fuel for a 100-kilometer drive. Moreover, prolonged low-speed idling can cause carbon buildup, especially in older cars, which may lead to malfunctions. If you really need to sleep, it's better to turn off the engine and open the windows, or invest in an inflatable car mattress and set up a tent outdoors—safer and more convenient.
