What Causes Severe Car Vibration When the AC is On?
2 Answers
Severe car vibration when the AC is on can be caused by excessive carbon deposits, fuel supply system malfunctions, aging engine mounts, or issues with the ignition coil or spark plugs. The operation of the AC increases the engine load, thereby exacerbating the vibration. Below are detailed explanations: Excessive Carbon Deposits: Severe carbon buildup in the engine cylinders can clog the spark plugs and valves, directly leading to car vibration at idle. Solution: Clean the engine promptly. Fuel Supply Malfunction: Issues in the fuel supply system, such as unstable fuel pressure, can cause fluctuations in the air-fuel mixture concentration, resulting not only in vibration but also unstable idling. Solution: Replace the fuel filter and check the fuel pressure. If abnormalities are detected, inspect the fuel pump. Aging Engine Mounts: Aging engine mounts can also lead to car vibration. If the engine vibration worsens without a loss of power, the issue may lie with the engine mounts. Solution: Replace the engine mounts. Ignition Coil or Spark Plug Issues: Misfiring is one of the most common causes of engine vibration, often due to problems with the ignition coil or spark plugs. Abnormalities in these components can cause the car to vibrate. Solution: Replace the ignition coil or spark plugs.
I've encountered this situation several times where the car shakes severely when the AC is turned on, especially during hot summer days when the compressor kicks in, causing a sudden increase in engine load and unstable RPM leading to shaking. The reasons could be excessive carbon buildup on the throttle body, an unresponsive idle control valve, aging spark plugs, or faulty ignition coils that fail to ignite properly under high load. If the compressor is loosely installed or has internal issues, it can also transmit strong vibrations to the car body. I recommend first checking the air filter and spark plugs yourself, cleaning any carbon deposits, and if the problem persists, it's best to visit a professional repair shop to scan for error codes with a diagnostic tool to accurately identify the root cause. Timely repairs are crucial; otherwise, prolonged issues can damage the engine, increase fuel consumption, and pose safety risks. Always perform a brief test drive before heading out to confirm everything is in order.
