Hyundai Acoustic Noise from Contactor or Transformer

Charger makes a loud humming or buzzing noise during operation.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loose mounting of main contactor, Worn contactor coil, Vibrating transformer or choke on power board, Excessive grid voltage causing magnetostriction noise

How to Fix / Troubleshooting

Safety first: Turn off power before opening the charger to inspect internal components.

  • Identify source: With the cover on, listen carefully to locate whether the noise comes from the top, bottom, or side of the unit.
  • Check mounting screws: With power OFF, tighten mounting screws for the contactor and any large inductors or transformers.
  • Normal vs abnormal: A soft hum can be normal; a loud, rattling buzz usually indicates a failing contactor or loose core.
  • If noise persists or worsens: Replace the noisy contactor or transformer assembly to prevent future failure.
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Repair Difficulty

Medium 3/5

Required Part

Main Contactor / Power Inductor
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