What it means
Differential pressure across the inlet air filter is above the expected limit.
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
- Restricted or dirty inlet air filter
- Inlet-filter differential-pressure switch or sensing problem
Operator-safe first checks
- Inspect the external intake path for obvious blockage.
- Check the filter service condition if it can be viewed without removing safety guards.
Trained maintenance / service checks
- Replace the inlet filter when indicated by the machine procedure.
- Check the inlet-filter differential-pressure switch and its connections if the warning persists with a known-good filter.
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.