Why does the new Mondeo idle shake when the air conditioning is on?
2 Answers
New Mondeo idle shake is caused by changes in the gas force inside the cylinders (a change in gas force in one cylinder or several cylinders), leading to an imbalance in power among the cylinders. This results in inconsistent horizontal component forces during the power stroke of each piston, creating an unbalanced moment that causes the engine to shake laterally. New Mondeo engine idle adjustment method: When the engine idle operation is unstable, adjustment should be made under normal engine temperature and when there are no faults in the oil or electrical systems. Definition of idle: Refers to the engine running without any load, only overcoming the frictional resistance of its internal components, without outputting power externally.
As a seasoned car enthusiast, I've noticed that the issue of engine idling vibration when the air conditioning is turned on in the new Mondeo is most commonly caused by a sudden increase in engine load. When the AC compressor is engaged, the engine requires additional power to drive it. However, at idle, the engine RPM is already low. If the fuel delivery system isn't operating smoothly—such as when the fuel injectors are partially clogged or the fuel pump output is unstable—it can easily lead to vibration. Additionally, if the engine control unit (ECU) is slow to adjust the idle speed, it can exacerbate this vibration. If left unaddressed, this issue may lead to increased engine wear over time and could even affect the ignition system. The significant load change when the AC is turned on can cause vibration if the ECU can't adjust the RPM quickly enough. I recommend getting the fuel system and spark plugs checked as soon as possible—cleaning the throttle body often resolves the issue. In daily use, try to avoid prolonged idling with the AC on to reduce load impact.
