Firman Over-Voltage Condition Without Code

Generator output voltage is consistently high (above nominal) but no specific error code is displayed.

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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

Misadjusted AVR, Faulty AVR sensing circuit, Loose neutral or sensing leads, Incorrect AVR replacement part

How to Fix / Troubleshooting

Safety first: High voltage can damage appliances. Turn OFF the generator and isolate it from the load before adjustments.

  • Inspect AVR wiring: Confirm that the AVR sensing leads are connected to the correct phases and neutral as per Firman wiring diagram.
  • Check neutral connection: Ensure the generator neutral bus and output neutral conductor are tight and free of corrosion.
  • Adjust AVR (if adjustable): Some AVRs have a small potentiometer for voltage adjustment. With a technician and proper meter, adjust to bring no-load voltage to specification.
  • Replace AVR: If voltage remains high or unstable, install a new Firman-compatible AVR.

Do not operate the generator with sustained over-voltage; sensitive electronics can be damaged.

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Repair Difficulty

Hard 4/5

Required Part

Automatic Voltage Regulator (AVR)
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