Is it okay to leave the engine running with the air conditioning on when parked?

[RoseLee]

It is possible to leave the engine running with the air conditioning on when parked, but it is not recommended to do so for extended periods. When the engine is idling with the air conditioning on, the engine needs to overcome the friction resistance of its internal components without delivering power externally. This leads to incomplete fuel combustion, which can cause carbon deposits to form in the cylinders and on the throttle valve. During engine idling, due to incomplete fuel combustion, the exhaust often contains high levels of carbon monoxide. This carbon monoxide, expelled with the exhaust, can accumulate around the vehicle and enter the cabin through the air conditioning system. Additionally, with the windows closed while the air conditioning is on, the lack of air circulation can cause the concentration of carbon monoxide inside the vehicle to rise over time.