What Causes the Car to Jerk at Low Speeds After Turning on the Air Conditioning?
1 Answers
The reasons for the car jerking at low speeds after turning on the air conditioning are as follows: 1. The engine control logic is faulty and cannot receive the signal indicating the air conditioning is on. When it cannot determine whether the air conditioning is on, the engine control unit (ECU) mistakenly interprets it as a temporary high load and attempts to compensate for the resistance at idle by increasing the engine speed. When the engine speed decreases, it cannot handle the load from the air conditioning compressor, causing the speed to increase again. This back-and-forth results in low-speed jerking. 2. The air conditioning control circuit is faulty and cannot send the signal indicating the air conditioning is on. Similar to the first point, because the ECU cannot determine the air conditioning's status, it continuously adjusts the idle speed, leading to low-speed jerking. 3. A fault in the air conditioning circuit causes the air conditioning to work intermittently. When the air conditioning is off, the compressor belt runs without load, so it does not affect the engine load. However, intermittent operation of the air conditioning compressor forces the engine to continuously adjust the idle speed, resulting in low-speed jerking. Fuel-injected engines are equipped with an engine control unit that manages and adjusts the appropriate idle speed to keep the engine running in a low-power state without stalling.
