1. Overview
When a rooftop package unit (RTPU) enters a fault or alarm condition, it will display an alarm icon on the controller home screen. Depending on the fault type, an audible alarm may also activate. The fault must be identified, recorded, and cleared before restarting the system.
This reset procedure applies to RTPU systems fitted with the AIRSTAGE control interface or touchscreen controller as used in Fujitsu General Australia and New Zealand installations.
2. Identifying an Active Alarm
If an alarm occurs:
An alarm triangle icon will appear on the main controller display.
In some cases, an audible tone will sound until the alarm is acknowledged.
To view the fault details:
Press the MENU button.
Navigate to ALARM STATUS.
Select ACTIVE ALARMS.
Review the displayed alarm message (e.g. “Circuit 1 High Pressure Alarm”).
Record the alarm description and time occurred before resetting.
3. Checking Alarm History (Optional)
To confirm past faults for service diagnostics:
Press MENU.
Select ALARM STATUS.
Choose ALARM HISTORY.
Review previously recorded alarms with timestamps.
Note: Alarm history helps identify recurring issues such as high pressure cut-outs, airflow faults, or communication errors.
4. Resetting the Alarm
After verifying the cause and ensuring the fault condition is cleared (e.g., filters cleaned, fan operational, pressure switches reset):
Option 1 – Via Controller Menu
Press MENU.
Select ALARM STATUS.
Choose RESET ALARMS.
Wait a few seconds for confirmation that alarms have cleared.
Option 2 – Manual Reset
Press and hold the ESC button on the controller for 5 seconds.
The audible alarm and alarm icon will clear if the fault is resolved.
If the alarm reoccurs, recheck operational parameters and correct the underlying cause before attempting another reset.
5. Post-Reset Check
After clearing alarms:
Return to HOME screen.
Verify the alarm icon is no longer visible.
Confirm normal operating values:
Supply air temperature
Compressor status
Fan operation
Return air reading
If applicable, perform a Test Run to ensure stable operation.
6. Common Causes of Alarms
| Alarm Type | Probable Cause | Corrective Action |
|---|---|---|
| High Pressure | Blocked filters, fan failure, overcharge | Check airflow, condenser coil, and refrigerant charge. |
| Low Pressure | Refrigerant leak, TXV fault, low airflow | Leak test and repair, verify suction pressure. |
| Fan Motor Alarm | Motor overload or sensor failure | Inspect fan motor, capacitor, and controller output. |
| Temperature Sensor Error | Disconnected or damaged sensor | Test thermistor resistance, replace if open/shorted. |
| Communication Error | Wiring fault between controller and PCB | Check comms wiring integrity and polarity. |
7. Notes for Technicians
Always record alarm details before clearing for future reference.
If alarms persist, contact Fujitsu Technical Support with:
Model and serial number
Alarm code or description
Site conditions (ambient temperature, load state)
Frequent resets without addressing the cause may lead to compressor or PCB damage.
8. Summary
To reset a Fujitsu RTPU:
Access MENU → ALARM STATUS.
Review ACTIVE ALARMS.
Rectify the cause.
Reset alarms via RESET ALARMS or hold ESC for 5 seconds.
Confirm the system returns to normal operation.
