On a Panrui screw compressor, the cooling fan starts at 80°C and stops at 75°C. If exhaust temperature keeps climbing past the controller's high limit, the unit does not simply "run hot." It stops, alarms, and the field-fault screen shows "Exhaust temperature high." Misreading that screw compressor alarm code, or clearing it before fixing the cause, turns a preventable trip into oil coking, bearing wear, and an air-end rebuild.
Where Screw Compressor Alarm Codes Appear
A Panrui unit reports faults in two places. The controller's Field Fault menu shows plain-language trips such as "Exhaust temperature high," "High exhaust pressure," "Phase sequence error," or "Temperature sensor failure." The variable-frequency drive records inverter faults as Fu codes, and it stores the last six fault records with output current, voltage, frequency, and module temperature at the moment of the trip.
Before touching a reset, open the Field Fault menu and the Historical Fault menu. The history tells you whether the code is new or recurring.
Common Alarm Messages and Their Causes
- Exhaust temperature high — blocked cooler fins, low oil level, a sticking thermal valve, or a faulty temperature sensor.
- High exhaust pressure — discharge pressure passed the set upper limit, often from a clogged oil separator or a minimum-pressure-valve problem.
- Phase sequence error — supply wiring reversed. The controller blocks start; swap any two phase conductors and verify rotation.
- Sensor failure — an open or poorly connected pressure or temperature sensor.
- Fu.14 — VFD overheat: air duct blocked, ambient temperature too high, or fan failure.
- Fu.17 — VFD output phase loss; check motor wiring.
- Fu.16 — external fault input received; trace the signal source.
- Fu.1 / Fu.2 — acceleration or deceleration time too short for the load.
How to Reset a Screw Compressor Alarm Safely
Reset only after the root cause is cleared. The Panrui manual gives a four-step restart sequence: read the fault indication, switch off the main power, troubleshoot and eliminate the fault, then re-energize and restart.
- Record the code and the last operating values before powering down.
- Fix the fault — clean the cooler, restore the oil level, repair the sensor, or correct the wiring.
- For VFD overload or overheat trips, wait five minutes before resetting so the drive cools.
- Reset once. On the panel, long-press the Reset/Back key when stopped, send an RS485 reset command, or cycle power as a last resort.
Do not hammer the reset button. If the code returns or will not clear, stop and inspect. The manual warns that repeated resets damage the inverter, and that a fault that cannot be reset means the cause is still present.
Numbers That Guide a Safe Reset
- Fan starts at 80°C and stops at 75°C.
- A standard 0.8 MPa twin-screw unit should run near 80°C exhaust temperature; laser-cutting machines at 1.6–2.0 MPa run 90–100°C.
- Air filters are normally replaced every 1,500–2,000 hours — sooner in dusty plants.
- The safety valve opens about 20% above nominal working pressure to protect the system.
Objection Handling
"Can I just clear the alarm and restart?" Only if the fault is cleared. Overload and overheat protection requires a five-minute cool-down, and repeated resetting damages the drive.
"Why does the same code keep coming back?" Because the cause was not removed. Use the six-record fault history to confirm whether the condition is recurring, then trace the circuit or component instead of clearing the message.
Get the Alarm Logic Right on Your Next Screw Compressor
Alarm codes are diagnostic evidence, not a nuisance to bypass. When you interpret them correctly and reset them safely, you protect the air end, the VFD, and production uptime. Compare controller and protection features across Panrui's range at rotary screw air compressor, review VSD fault behavior at variable speed screw compressors, or ask an engineer to map your specific codes at contact Panrui.
