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Fujitsu Halcyon / Airstage splits Error Codes
Fujitsu uses one numbering scheme across many systems, but not every code applies to every model. Wall-mount singles mostly show the communication, sensor, fan and outdoor codes.
| Code | Meaning | What to check |
|---|---|---|
| 11 (1-1) | Serial communication error. | Interconnect wiring, terminals, splices. How to fix → |
| 12 (1-2) | Wired remote controller communication error. | |
| 14 (1-4) | Network communication error. | |
| 15 (1-5) | Check run unfinished. | |
| 16 (1-6) | Transmission / peripheral connection error. | |
| 21 (2-1) | Refrigerant circuit address setting error. | |
| 22 (2-2) | Indoor unit capacity error. | |
| 23 (2-3) | Combination error (indoor/outdoor mismatch). | |
| 24 (2-4) | Connection unit number error. | |
| 26 (2-6) | Address setting error. | |
| 27 (2-7) | Master/slave unit setup error. | |
| 29 (2-9) | Connection unit number error in wired remote circuit. | |
| 31 (3-1) | Power supply interruption error. | Supply voltage and connections. How to fix → |
| 32 (3-2) | Indoor PCB EEPROM error. | Indoor control board. |
| 35 (3-5) | Manual auto switch error. | Stuck manual/auto button. |
| 3A (3-10) | Indoor unit wired remote communication error. | |
| 41 (4-1) | Inlet air temperature sensor error. | Measure the thermistor; check connector. How to fix → |
| 42 (4-2) | Indoor heat exchanger middle temperature sensor error. | Measure the thermistor; check connector. How to fix → |
| 51 (5-1) | Indoor unit fan motor error. | Fan motor, connector, blower wheel binding. |
| 52 (5-2) | Indoor electronic expansion valve error. | |
| 53 (5-3) | Drain pump error. | Drain pump, float, plugged drain. |
| 57 (5-7) | Damper error. | |
| 58 (5-8) | Intake grille error. | |
| 5U (5-15) | Indoor unit error. | |
| 62 (6-2) | Outdoor PCB / communication error. | |
| 63 (6-3) | Inverter error. | Inverter board and compressor. How to fix → |
| 64 (6-4) | Active filter / PFC circuit error. | |
| 65 (6-5) | Trip terminal 'L' error. | |
| 6A (6-10) | Display PCB / communication error. | |
| 71 (7-1) | Outdoor discharge temperature sensor error. | Measure the thermistor; check connector. How to fix → |
| 72 (7-2) | Compressor temperature sensor error. | How to fix → |
| 73 (7-3) | Outdoor heat exchanger liquid temperature sensor error. | How to fix → |
| 74 (7-4) | Outdoor ambient temperature sensor error. | How to fix → |
| 75 (7-5) | Outdoor suction refrigerant temperature sensor error. | How to fix → |
| 76 (7-6) | 2/3-way valve temperature sensor error. | How to fix → |
| 77 (7-7) | Outdoor heat sink temperature sensor error. | How to fix → |
| 82 (8-2) | Sub-cool inlet/outlet temperature sensor error. | How to fix → |
| 83 (8-3) | Outdoor liquid pipe temperature sensor error. | How to fix → |
| 84 (8-4) | Outdoor current sensor error. | How to fix → |
| 86 (8-6) | High/low pressure sensor or switch error. | |
| 94 (9-4) | Outdoor current trip detection. | Compressor, refrigerant system, supply voltage. How to fix → |
| 95 (9-5) | Compressor rotor location detection error. | Compressor wiring and inverter output. How to fix → |
| 97 (9-7) | Outdoor fan motor error. | Outdoor fan motor, obstruction, connector. |
| 98 (9-8) | Outdoor fan motor 2 error. | |
| 99 (9-9) | Four-way valve error. | Reversing valve coil and operation. |
| 9A (9-10) | Coil (expansion valve) error. | |
| 9U (9-15) | Outdoor unit error. | |
| A1 (10-1) | Outdoor abnormal discharge temperature. | Low charge or restriction. How to fix → |
| A3 (10-3) | Abnormal compressor temperature. | |
| A4 (10-4) | High pressure error. | Dirty outdoor coil, fan, overcharge, restriction. |
| A5 (10-5) | Low pressure error. | Low charge (leak), restriction, closed valve. How to fix → |
How to read the codes
- With an error, the ECONOMY lamp blinks continuously. Count the OPERATION lamp blinks for the first digit and the TIMER lamp blinks for the second.
- Example: OPERATION 5, TIMER 1 = code 51 (indoor fan motor). TIMER 10 = A, 15 = U on wired remotes.
- Errors display only during operation.
Codes point to a circuit, not a part. Test before replacing boards or sensors. Inverter boards hold a dangerous charge after power-off; wait and verify DC bus voltage is gone before touching them. Refrigerant work requires EPA 608 certification.
Source: Fujitsu General (UK) Fault Codes reference. The "meaning" column follows the manufacturer's wording; "what to check" is our field summary. Always go by the label on the furnace you're working on.
Related
- Mini-split communication error troubleshooting
- Mini-split flare connections (the usual leak point)
- Look up any mini-split code
Other brands
- Daikin FTX / FVXS / FDMQ with RXL outdoor (19 Series)
- MRCOOL DIY E Star 4th Generation
- Mitsubishi Electric MSZ-GL / MSY-GL (failure mode recall)
- Senville AURA / LETO
- LG Single / multi-split wall units (CH codes)
- Gree Livo / All-Match with LIV outdoor (R-32)
- Pioneer Diamante / Quantum (WYT-17, WYT-20, WYT-24, WYT-25, WYT-FA)
- Lennox Mini-splits: MLB / MPC / 3PC outdoor with M22A, M33C, MWMC, MCFA/B, MFMA indoor
- ACiQ Single-zone wall mount, R-454B (ACiQ-xxWS / -xxW-BL with -xxZS / -xxZPL outdoor)
- Midea High wall ductless DLFSHB (DLFSHBH09XAK, -12XAJ, -12XAK, -18XAK, -24XAK)
- Klimaire KSIE inverter wall mount (2014–2016 models, e.g. KSIE012-H120-SW)
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