What it means
The emergency-stop circuit is active, or the controller is seeing an E-stop input that remains active.
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
- Emergency-stop button is pressed
- Faulty E-stop button or E-stop circuit wiring
Operator-safe first checks
- Confirm why the E-stop was used before attempting a restart.
- If it was pressed for a real hazard, correct the hazardous condition first.
- Release the button only when it is safe and authorized to do so.
Trained maintenance / service checks
- If the message remains with the button released, inspect the E-stop circuit and wiring under lockout/tagout.
- Verify the safety circuit functions correctly before returning the compressor to service.
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: 31.