What it means
The controller is not seeing the expected sump pressure for the machine state.
The STS troubleshooting table links this message to either a pressure-sensing problem or a compressor that did not actually start correctly.
Likely causes
- Pressure sensor, connection, wiring or tubing problem
- Machine failed to start or did not reach the expected operating state
Operator-safe first checks
- Confirm whether the main motor actually started and note any other simultaneous faults.
- Record the sump-pressure value shown on the controller.
- Do not loosen pressure tubing or fittings on a pressurized package.
Trained maintenance / service checks
- Check the pressure sensor, wiring, connections and sensing tubing.
- Diagnose the start sequence if the machine failed to start.
Can the compressor keep running?
No. Diagnose the failed start or pressure-sensing condition before returning the compressor to service.
Source confidence
OEM VERIFIED
Sullair identifies bad sensor/connections or a failed start as causes of Low Sump Pressure.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page(s): 33.