What it means
Fluid pressure is below the value expected by the controller for safe operation.
The troubleshooting guide treats this as a condition requiring correction before normal operation.
Likely causes
- Clogged fluid filter
- Low sump fluid level
- Low ambient temperature affecting fluid behavior
- Fluid pump failure on packages that use a pump
Operator-safe first checks
- Record ambient temperature and whether the problem occurs only during cold starts.
- Check maintenance history for an overdue fluid filter.
- Do not open the fluid system until the package is safely isolated and depressurized.
Trained maintenance / service checks
- Inspect/replace the fluid filter if restricted.
- Verify fluid level using the model-specific procedure.
- Evaluate cold-weather requirements and sump-heater needs where applicable.
- Check fluid-pump operation on configurations that use one.
Can the compressor keep running?
No. Low lubrication/fluid pressure can quickly damage the airend or other components.
Source confidence
OEM VERIFIED
Sullair lists a clogged filter, low fluid level, low ambient temperature and fluid-pump failure.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page(s): 33.