What it means
Interstage pressure is abnormally high on a multi-stage package.
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
- Interstage flow restriction
- Second-stage or air-end problem
Operator-safe first checks
- Stop escalation if abnormal noise, heat or vibration is also present.
- Record the pressure reading and operating condition when the fault occurred.
Trained maintenance / service checks
- Inspect the interstage flow path for restriction.
- Evaluate the second stage/air end using the machine-specific service 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: 31.