What it means
The controller expected high-voltage starter power but did not detect it.
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
- Disconnect switch open
- Main motor fuse or circuit breaker open
- No power to high-voltage starter
Operator-safe first checks
- Verify site power status and whether an upstream disconnect was intentionally opened.
- Do not enter or open high-voltage equipment unless qualified and authorized.
Trained maintenance / service checks
- Check the disconnect, main motor fuses/circuit breaker and starter power using the site electrical 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: 32.