General Assist Technical Reference
J-Series VRF – Compressor Diagnostic Guide
Part Number
9372716014 – Compressor ASSY
Applicable system: Fujitsu General J-Series VRF
9372716014 – Compressor ASSY
Applicable system: Fujitsu General J-Series VRF
Safety
Isolate power before checking compressor wiring or winding resistance. Live current and operational checks must only be completed by qualified technicians using appropriate electrical safety procedures.
Isolate power before checking compressor wiring or winding resistance. Live current and operational checks must only be completed by qualified technicians using appropriate electrical safety procedures.
1. Check Circuit Connection
Verify terminal wiring between the TR PCB ASSY and the compressor.
U = Red V = White W = Black
- Confirm U, V and W are connected to the correct compressor terminals.
- Check that each terminal is secure.
- Confirm the terminal cover is correctly fitted.
2. Operation Check
During normal compressor operation, use system pressure, discharge temperature and operating current to help determine the likely fault condition.
| Check | Observed Condition | Possible Cause |
|---|---|---|
| Pressure | Pressure decreases | Low refrigerant charge |
| Pressure | Pressure does not decrease | Possible refrigerant piping blockage |
| Discharge Temperature | Temperature increases | Low refrigerant charge |
| Operating Current | Current increases | Low refrigerant charge |
| Operating Current | Current rises sharply | Locked compressor / mechanical fault |
3. Compressor Winding Resistance
Measure resistance between all compressor terminal pairs:
| Measurement Points | Expected Resistance |
|---|---|
| U–V / V–W / W–U | 0.187 Ω |
Replace the Compressor
If the winding resistance measures 0 Ω (short circuit) or ∞ Ω (open circuit), replace the compressor.
If the winding resistance measures 0 Ω (short circuit) or ∞ Ω (open circuit), replace the compressor.
4. Cooling Test Operation
Verify compressor speed behaviour during cooling test operation.
Speed Reference
1 cycle = 3 Hz for the 6-pole permanent magnet motor.
1 cycle = 3 Hz for the 6-pole permanent magnet motor.
| Test Stage | Compressor Speed | Approx. Duration |
|---|---|---|
| Hold 1 | 50 rps | 230 seconds |
| Hold 2 | 70 rps | 550 seconds |
| After Hold Periods | Gradual increase | As system load stabilises |
Clamp Meter Check
Use a clamp meter on the U (Red) phase output from the TR PCB ASSY to verify current and speed stability during test operation.
Use a clamp meter on the U (Red) phase output from the TR PCB ASSY to verify current and speed stability during test operation.
5. Diagnostic Summary
| Check | Test Point | Normal Condition | Action if Abnormal |
|---|---|---|---|
| Wiring | TR PCB → Compressor | U, V and W secure | Reconnect or replace harness |
| Pressure | Suction / Discharge | Expected pressure response on start-up | Inspect refrigerant condition or blockage |
| Resistance | U–V / V–W / W–U | 0.187 Ω | Replace compressor if short/open |
| Current | Clamp test | Stable rise | Check PCB or compressor motor if erratic |
6. Reference Image
The original Freshdesk-hosted diagnostic reference is retained below.
