Is it okay to leave the engine running with the AC on while waiting in the car?
2 Answers
It is possible to leave the engine running with the AC on while parked, but it is not recommended for extended periods. When the engine is idling with the AC on, the engine must overcome internal friction without delivering power to the wheels, leading to incomplete fuel combustion. This can result in carbon buildup in the cylinders and throttle body. During idle operation, incomplete combustion also produces high levels of carbon monoxide in the exhaust, which can accumulate around the vehicle and enter the cabin through the AC system. With the windows closed and no air circulation, the concentration of carbon monoxide inside the car can gradually increase over time.
I often turn on the air conditioning while waiting for clients by the roadside. To be honest, this habit is quite damaging to the car. Idling with the AC on for half an hour can burn nearly two liters of fuel, not to mention the most critical issue: prolonged low-speed engine operation leads to incomplete combustion, causing carbon buildup in the throttle valve. Last week, my car just had its carbon deposits cleaned, which were caused by long-term idling at traffic lights. Moreover, many cities now have regulations imposing fines for idling over three minutes, and getting caught by traffic police can cost at least 200 yuan. If you really need to use the AC, it's recommended to switch to recirculation mode, which saves one-third more fuel than fresh air mode, and it's best not to exceed twenty minutes.
