What it means
An auxiliary motor circuit—such as a cooling fan, fluid pump, or another configured motor—has tripped its overload protection.
This entry is tied to the exact STS message family documented by Sullair. The same words can mean something different on another controller generation, so confirm the displayed message and machine documentation before acting.
Likely causes
- Auxiliary motor overload has tripped
- Motor current may be higher than expected
- Loose electrical connection
- Starter contact problem
- Low incoming line voltage
Operator-safe first checks
- Record which auxiliary device was running when the message appeared.
- Look for an obvious blocked airflow path or external obstruction without removing guards.
- Do not repeatedly reset an overload that trips again.
Trained maintenance / service checks
- Allow the overload element to cool before following the machine-specific reset procedure.
- Verify motor current against the configured/rated value.
- Inspect starter contacts, wiring integrity and incoming line voltage under an authorized electrical procedure.
Reset or keep running?
Do not use repeated resets as a substitute for diagnosis. If the condition involves electrical power, a motor overload, high pressure, loss of cooling, abnormal temperature, or a safety circuit, correct the underlying problem before returning the compressor to service.
Source confidence
OEM VERIFIED
This message and its troubleshooting direction are traced to the Sullair STS controller troubleshooting guide.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page: 30.