What Causes Engine Shaking When the AC is On?

[EdwardLynn]

Engine shaking when the AC is on can be attributed to the following reasons: 1. Severe Engine Carbon Buildup: The most common cause of shaking is a dirty throttle body or excessive carbon deposits in the fuel injectors. When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold-start injector can be largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making it difficult to start. The solution is to clean the fuel system and check if the idle control valve has carbon buildup, which should be cleaned thoroughly. 2. Unstable Fuel Pressure: Check whether the fuel supply pressure and the intake pressure sensor are functioning properly. If the fuel pump's supply pressure is abnormal or the intake pressure sensor's readings are incorrect or malfunctioning, it can cause the vehicle to shake. The solution is to check the fuel pressure and replace the components if necessary. 3. Aging Engine Components: Vehicle shaking can also be related to aging engine mounts. Engine mounts are essentially the shock absorption system of the engine, responsible for absorbing minor vibrations during engine operation.