If the air conditioner is not turned on, the idle speed is normal. If the air conditioner is turned on, the idle speed is unstable and high. What is the reason? ?

Because starting the cold air conditioner and air conditioning compression will lose the power of the engine, in order to stabilize the idle speed, the idle speed will be higher, about 900 rpm. If the idle speed of your car's air conditioner is higher than 900 rpm, the tachometer pointer will shake up and down, which may be caused by too much carbon deposit on the accelerator. I suggest you clean the throttle, and remove the throttle to clean it, so as to be clean. If it is an electronic throttle, you need to re-learn the idle speed with a professional computer after cleaning. If it is a traditional cable throttle, it is necessary to clean not only the throttle, but also the idle motor. Do not start the vehicle immediately after cleaning. Turn the car key to the electric switch position first, and repeat 1 2 times to reset the idle motor. After that, start the vehicle and it will be OK.