Why does the engine shake severely when the air conditioning is turned on?
2 Answers
Air conditioning is turned on the engine shake reasons are as follows: Inappropriate air-fuel ratio: The air-fuel mixture ratio is inaccurately adjusted, occurring in both open-loop and closed-loop control systems. In vehicles with closed-loop control, the oxygen sensor's minimum operating temperature is 370 degrees Celsius. If the vehicle has just been started, the exhaust pipe temperature may not reach 370 degrees Celsius, causing the oxygen sensor not to function. Low temperature: The engine's internal temperature is insufficient, and both fuel and lubricant temperatures are too low. Therefore, during a cold start, more fuel should be injected to meet power requirements. The larger the spark plug gap, the smaller the ignition energy. At low temperatures, fuel atomization is poor, requiring higher ignition energy. Over time, the spark plug's ignition gap tends to widen, reducing ignition energy and consequently affecting engine performance, leading to vehicle shaking. Faulty coolant temperature sensor: The coolant temperature sensor is one of the key inputs for the engine control unit (ECU) to determine engine operating conditions. If the engine's cold start temperature is minus 10 degrees Celsius, but the ECU injects fuel based on a 20-degree Celsius condition, the fuel quantity will naturally be insufficient, resulting in engine shaking.
As an experienced driver who has been behind the wheel for many years, I feel that the engine shakes violently as soon as the air conditioning is turned on, which is mostly caused by a sudden increase in engine load. For example, when the air conditioning compressor starts, it requires extra effort from the engine. If the spark plugs or ignition coils are aged or worn, the engine will shake continuously under heavy load. Alternatively, if the compressor itself has issues or the clutch isn't functioning properly, it can make the engine unstable. In some cars, if the idle speed regulator is dirty or clogged, the RPM drops too low when the air conditioning is turned on, directly causing shaking. It's recommended to first check the condition of the spark plugs; if they are eroded or blackened, replace them with new ones. Also, check if the compressor belt is loose—if it's too loose, it can slip and increase the load. Regular maintenance should include cleaning the throttle body to prevent such situations. If not addressed promptly, sudden shaking while driving could lead to stalling. Safety comes first, so it's best to have it checked at a professional shop.
