Quincy Compressor Fault Codes — Quick Reference
Quincy rotary screw compressors use controller alarms for high temperature, motor overload, pressure switch problems, and service intervals. QGS and QGV units also carry VSD-related alarms on variable-speed models.
| Alarm | Meaning | Quick Fix |
|---|---|---|
| High Temp | Discharge or oil temp too high | Clean coolers; check oil |
| Motor Overload | Main motor current high | Check load and voltage |
| Pressure Sensor Fault | Bad transducer signal | Inspect sensor and wiring |
| Phase Fault | Input phase loss / reversal | Check incoming power |
| VSD Fault | Drive-level trip | Read drive history |
| Service Alarm | PM due | Perform scheduled maintenance |
| E-Stop | Emergency stop active | Reset circuit |
| Low Oil Shutdown | Lubrication issue | Check oil and filters |
Most Common Faults
High Temp
High-temperature alarms on Quincy screws are almost always maintenance-related. Dirty coolers, wrong oil, low oil level, or failed fan motors are the first checks. Cleanliness matters more than people realize on screw compressors.
Phase Fault
If a Quincy compressor shows a phase fault after electrical work, verify phase sequence and voltage balance at the disconnect. Loose lugs and weak contactors create intermittent phase-loss alarms under load.
Pressure Sensor Fault
A dead or drifting pressure transducer makes the controller do strange things, including bad load/unload behavior and nuisance shutdowns. Compare the controller pressure reading to a calibrated mechanical gauge before replacing valves.
Parts Often Needed
| Part | Notes |
|---|---|
| Pressure transducer | Amazon | Frequent electronic failure |
| Air/oil separator | Amazon | Major service item |
| Oil filter | Amazon | Replace during PM |
| Fan motor / contactor | Amazon | Check on temperature faults |
When to Call a Pro
If the compressor is tripping on high temp after cooler cleaning and PM service, the oil thermostatic valve or airend may be wearing out. That is specialist work.