AL14
Kohler-SDMO Generator Overvoltage Protection Trip

Controller displays AL14 / Alternator Overvoltage while running under light 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

Faulty AVR (Automatic Voltage Regulator), Incorrect AVR sensing wiring, Loose or broken voltage sensing leads, Incorrect voltage setpoint on AVR

How to Fix / Troubleshooting

Safety first: Open the generator output breaker and isolate the generator from the load. Turn controller to OFF and disconnect battery negative before opening alternator terminal box.

  • Measure output voltage: With the generator running in MANUAL and no load, measure line-to-line voltage. Compare to nameplate (e.g. 400 V). If significantly high, suspect AVR or sensing.
  • Inspect AVR connections: Locate the AVR in the alternator terminal box (e.g. Leroy-Somer alternator on Kohler-SDMO sets). Check sensing wires (usually marked 0–220/400 V) for tightness and damage.
  • Check AVR settings: Some AVRs have a voltage adjustment pot. If misadjusted, carefully reduce voltage to nominal while monitoring with a meter. Do not exceed manufacturer limits.
  • Replace AVR: If voltage is unstable or uncontrollable, replace the AVR with the correct Kohler-SDMO specified model.
  • Reset alarm: After corrections, clear AL14 and test under gradual load.

Incorrect AVR wiring or settings can damage connected equipment; if unsure, involve a qualified electrician.

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Repair Difficulty

Hard 4/5

Required Part

Automatic Voltage Regulator (AVR)
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