General Assist Technical Reference
JIII Outdoor Unit Wiring Diagram
AJ*040LBLAH, AJ*045LBLAH and AJ*054LBLAH
Power circuit, inverter section, fans, valves, sensors and control-board connections
This article provides a technician-oriented overview of the outdoor-unit wiring diagrams for JIII models AJ*040LBLAH, AJ*045LBLAH and AJ*054LBLAH. The 040/045 models share one diagram; the 054 model is shown separately but uses the same overall electrical architecture.
Electrical safety: These units contain 230 V AC mains and high-voltage DC within the inverter section. Isolate the unit, prove dead and allow the DC bus to discharge before disconnecting plugs, testing resistance or handling PCB assemblies.
1. Applicable models
| Diagram | Models |
|---|---|
| Page 1 | AJ*040LBLAH, AJ*045LBLAH |
| Page 2 | AJ*054LBLAH |
2. Main power and inverter circuit
The wiring diagram shows the outdoor unit supplied from 230 V ~ 50 Hz. The mains supply passes through the terminal and noise-filter section before supplying the control and inverter circuits.
| Section | Function / wiring shown |
|---|---|
| Power terminal | 230 V AC supply and earth connection. |
| Noise Filter Board | Filters incoming supply before distribution to the outdoor electronics. |
| Fuse F502 | 5 A, 250 V fuse shown on the noise-filter board. |
| Control Board | Receives thermistor, pressure and external-input signals and commands fans, valves and the inverter section. |
| Active Power Module | Connected with the choke coil and inverter circuitry as part of the DC power-conditioning stage. |
| Inverter Board | Produces the variable-frequency three-phase output for the compressor. |
| Compressor | Three-phase motor connected to inverter output R / S / T via terminals TM403, TM404 and TM405. |
Important: Do not use the incoming 230 V supply as a reference for measurements on the inverter output. Compressor drive is generated electronically and must be tested using the appropriate inverter/compressor procedure.
3. Outdoor loads controlled by the PCB
| Load | Description |
|---|---|
| Fan motor 1 – Upper | Electronically controlled outdoor fan motor connected to the control board. |
| Fan motor 2 – Lower | Second outdoor fan motor shown in the circuit. |
| Expansion Valve Coil 1 | Electronic expansion valve stepper-motor coil. |
| Expansion Valve Coil 2 | Second electronic expansion valve stepper-motor coil. |
| 4-Way Valve Coil | Reversing-valve solenoid output. |
| Solenoid Coil | Additional refrigerant-circuit solenoid output shown as SV. |
| Crankcase Heater | Heater circuit controlled from the outdoor control section. |
4. Sensors and feedback devices
The control board monitors refrigerant pressures and multiple thermistors. The diagram identifies the following devices:
- Pressure Sensor (High)
- Pressure Sensor (Low)
- Pressure Switch
- Thermistors TH1, TH10, TH7, TH8, TH9, TH4, TH5 and TH3
| Thermistor reference | Wire colour shown |
|---|---|
| TH1 | Blue |
| TH10 | White |
| TH7 | Green |
| TH8 | White |
| TH9 | Brown |
| TH4 | Red |
| TH5 | Pink |
| TH3 | Identified by marking tube |
5. External / inter-unit connections
The terminal section provides connections to the indoor-unit network and external input/output circuits. When diagnosing communication or external-control faults, confirm the correct terminal assignment against the model-specific wiring diagram before moving any conductors.
6. Recommended diagnostic sequence
- Confirm supply: verify the correct 230 V AC supply at the outdoor terminal and confirm earth continuity.
- Check F502: inspect the 5 A / 250 V fuse on the noise-filter board if the unit is completely dead.
- Check PCB connections: inspect plugs between the noise-filter board, control board, active power module and inverter board.
- Identify the failed load: fan, EEV, solenoid, 4-way valve, crankcase heater or compressor.
- Check feedback: inspect pressure sensors, pressure switch and thermistor connectors for loose, open or damaged wiring.
- Use the exact wiring diagram: compare connector numbers and wire colours before measuring or replacing components.
Technician tip: The 040/045 and 054 diagrams are very similar. Always confirm the model number first so that the correct connector location and component arrangement are used during diagnosis.
Technical reference prepared from the supplied JIII outdoor-unit wiring diagrams. Use the original service documentation for final connector identification, component resistance values and live-voltage test procedures.