Firman Under-Voltage Condition Without Code

Generator output voltage is consistently low (below nominal) with no error code present.

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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

Weak engine (low RPM under load), Failing AVR, Partially shorted stator winding, Excessive load connected

How to Fix / Troubleshooting

Safety first: Turn OFF the generator and disconnect from the load before testing.

  • Check engine speed: With a frequency meter, verify frequency is near 60 Hz at no load. Low frequency indicates a governor or engine power issue.
  • Reduce load: Disconnect non-essential loads and retest voltage. If voltage recovers, your load exceeds the generator's capacity.
  • Inspect AVR: Check connections and replace the AVR if voltage remains low with correct engine speed and light load.
  • Test stator: A technician should perform resistance and insulation tests on the stator to rule out partial shorts.

Persistent low voltage can overheat motors and electronics; correct the issue before regular use.

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Repair Difficulty

Hard 4/5

Required Part

Automatic Voltage Regulator (AVR)
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