AL24
Kohler-SDMO Overfrequency Protection Trip

Controller displays AL24 / Frequency High and disconnects load

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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

Governor overspeed setting too high, Faulty engine speed sensor, Incorrect frequency configuration in controller, Mechanical governor spring misadjusted

How to Fix / Troubleshooting

Safety first: Open the generator breaker and set controller to OFF before adjusting speed or governor components.

  • Verify configuration: Check that the controller is configured for the correct nominal frequency (50 or 60 Hz) for your region and generator.
  • Inspect speed sensor: Check the magnetic pickup sensor for correct gap and secure mounting.
  • Adjust governor: On mechanical governors, adjust the speed setting screw slightly to reduce speed while monitoring frequency with a meter.
  • Electronic governor: For electronic governors, follow Kohler-SDMO procedures to recalibrate speed setpoint.
  • Reset alarm: Clear AL24 and test under load, ensuring frequency remains within tolerance.

Incorrect frequency can damage connected equipment; if you are not experienced with governor adjustment, contact a technician.

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Repair Difficulty

Hard 4/5

Required Part

Governor Actuator / Speed Control
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