Control panel shows UNDER FREQUENCY or RPM LOW; lights may dim and motors may sound strained when on generator power.
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Turn the generator OFF and open the main breaker. Do not run with low frequency as it can overheat motors.
- Inspect throttle and governor: With the engine off, move the throttle linkage by hand to ensure free movement. Remove debris or corrosion from pivot points.
- Check fuel supply: Confirm LP tank level or NG supply pressure with your gas provider. Undersized gas piping can cause low power under load.
- Reduce load: Temporarily turn off large loads (HVAC, electric water heater) and retest. If frequency stabilizes, you may be overloading the generator.
- Controller reset: Clear the fault and run a no-load test. If frequency remains low, governor adjustment or repair is needed.
When to call a technician: Governor and frequency adjustments require a tachometer and manufacturer specs. A technician should set engine speed and verify frequency under load.
Repair Difficulty
Required Part
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