What it means
Communication between compressors participating in a sequence is not healthy.
The STS warning description identifies a communication problem between sequenced controllers; the troubleshooting table adds cable/connection faults and incorrect sequence settings.
Likely causes
- Cable or connection fault between compressors
- Improper sequencing adjustments or settings
Operator-safe first checks
- Confirm the other sequenced compressors are powered and their controllers are online.
- Record which machines dropped out of sequence and when the warning appeared.
- Do not change sequencing parameters unless you understand the plant's load-sharing setup.
Trained maintenance / service checks
- Check inter-controller communication wiring and terminations.
- Verify sequence settings on every compressor participating in the sequence.
Can the compressor keep running?
The compressor may still be able to run locally depending on configuration, but automatic sequencing may be unreliable until communication is restored.
Source confidence
OEM VERIFIED
Sullair identifies inter-compressor wiring/connections and sequence settings as the primary causes.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page(s): 20, 34.