What it means
System line pressure is below the expected pressure because supply is not keeping up with demand or air is escaping from the system.
The compressor may run but fail to maintain the plant pressure requirement.
Likely causes
- Compressed-air demand exceeds available capacity
- Leaks or open lines in the air distribution system
Operator-safe first checks
- Look for a sudden plant demand increase or recently opened air-consuming equipment.
- Check for obvious open valves, disconnected hoses or audible major leaks in safe accessible areas.
- Compare line pressure while loaded against the normal operating baseline.
Trained maintenance / service checks
- Leak-test and repair the distribution system.
- Confirm compressor capacity and control settings against actual plant demand.
- Assess whether additional capacity or storage is required if demand consistently exceeds supply.
Can the compressor keep running?
Usually this is a capacity/system problem rather than an immediate protective shutdown, but production equipment may malfunction at inadequate pressure.
Source confidence
OEM VERIFIED
Sullair lists excess demand and leaks/open supply lines as the troubleshooting causes.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page(s): 32.