What Causes Engine Vibration When the Air Conditioner is On in an Elantra?

[KaydenAnn]

Engine vibration when the air conditioner is on can be caused by the following reasons: 1. Engine control logic error, unable to receive the signal of air conditioner activation: When the system cannot determine whether the air conditioner is on, the Engine Control Unit (ECU) mistakenly perceives it as a temporary high load and attempts to compensate by increasing the engine speed to counteract the resistance during vibration. When the engine speed decreases, it cannot handle the load from the air conditioner compressor, causing the speed to increase again. This back-and-forth adjustment manifests as engine vibration. 2. Air conditioner control circuit error, unable to send the air conditioner activation signal: Since the system cannot determine the air conditioner's status, the ECU continuously adjusts the engine speed, resulting in engine vibration. 3. Air conditioner circuit malfunction, causing intermittent operation of the air conditioner: When the air conditioner is off, the compressor belt runs idle without load, so it does not affect the engine load. However, intermittent operation of the air conditioner compressor causes the engine to continuously adjust its speed, leading to engine vibration.