There is abnormal noise when the car is idling, and it disappears as soon as the air conditioner is turned on.

First, the throttle, idle motor or air intake caused by excessive carbon deposition. Due to carbon deposition in the air inlet, the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake air volume, resulting in the mixture being too rich or too lean, which leads to the engine not being started.

Second, there is a slight leakage from the fuel nozzle, which causes the fuel to leak into the combustion chamber for a period of time after the vehicle is turned off, resulting in too rich mixture when restarting, which eventually leads to difficulties in starting.

Third, the activated carbon canister was damaged. If the solenoid valve is always on, the mixture at the engine intake will always be rich, which will cause the mixture to be too rich when the car is hot.