Applies to:
- Indoor units (ARTH): ARTH65KBTA / ARTH65KRTA / ARTH72KRTA / ARTH90KRTA (manual also references ARTH60KHTB / ARTH65KHTA / ARTH72KHTA / ARTH90KHTA)
- Outdoor units (AOTH): AOTH65KBTA / AOTH65KRTA / AOTH72KRTA / AOTH90KRTA
- Optional controllers: Wired remote controller options including 2-wire and 3-wire types (refer to applicable controller manual)
Contents
- 1) Safety and compliance
- 2) R32 refrigerant requirements
- 3) Tools and materials (R32/R410A rated)
- 4) System overview (what powers what)
- 5) Refrigerant piping requirements
- 6) Electrical requirements
- 7) Outdoor unit installation (AOTH)
- 8) Indoor unit installation (ARTH – duct type)
- 9) Pressure test, evacuation, commissioning
- 10) Additional refrigerant charging (AOTH)
- 11) Wired remote controller (optional) – quick reference
- 12) Test run and handover
- 13) Pump down (forced cooling operation) – Outdoor unit reference
- 14) Error codes (ARTH reference list)
1) Safety and compliance
- Installation and service work must be performed by appropriately licensed / authorised personnel in accordance with local regulations.
- Isolate electrical supply before removing covers or touching terminals.
- Do not energise the system until all installation work is complete and covers are fitted.
- If refrigerant leakage occurs during works: ventilate immediately and remove ignition sources.
- Use vacuum pump evacuation (do not purge with refrigerant).
- Ensure correct grounding/earthing and earth leakage protection as required by local regulations.
2) R32 refrigerant requirements
- R32 is a flammable refrigerant. Comply with applicable safety standards and local regulations for flammable refrigerants.
- Only use R32/R410A-rated tools, hoses and materials.
- Prevent moisture/foreign matter entering piping; seal pipe ends during storage/handling.
- Leak detection must be suitable for flammable refrigerants; do not use open flame methods.
3) Tools and materials (R32/R410A rated)
- High-pressure gauge manifold suitable for R32/R410A
- R32/R410A charging hoses
- Vacuum pump and appropriate adapters (as required)
- R32/R410A compatible leak detector
- Tube cutter, deburr tool, flare tool suitable for R32/R410A, torque wrenches for flare nuts and caps
- Nitrogen cylinder + regulator for pressure testing
4) System overview (what powers what)
- Indoor unit is powered from the outdoor unit. Do not provide a separate power supply to the indoor unit unless explicitly specified by local product documentation.
- Confirm indoor-to-outdoor terminal numbering matches on both ends.
- Route cables to avoid contact with refrigerant piping and moving parts; secure with cord clamps.
5) Refrigerant piping requirements
5.1 Copper pipe material and minimum wall thickness (R32/R410A)
- Use seamless phosphor deoxidised copper.
- Do not reuse existing piping (risk of contamination and incompatibility).
| Outside diameter | Nominal size | Minimum thickness (annealed copper) |
|---|---|---|
| 6.35 mm | 1/4" | 0.80 mm |
| 9.52 mm | 3/8" | 0.80 mm |
| 12.70 mm | 1/2" | 0.80 mm |
| 15.88 mm | 5/8" | 1.00 mm |
| 19.05 mm | 3/4" | 1.20 mm |
5.2 Line sizes (ARTH indoor unit)
| Indoor model group | Liquid pipe | Gas pipe |
|---|---|---|
| ARTH60 / ARTH65 class | 9.52 mm (3/8") | 15.88 mm (5/8") |
| ARTH72 / ARTH90 class | 12.70 mm (1/2") | 19.05 mm (3/4") |
5.3 System piping limits (AOTH outdoor reference)
- Minimum piping length: 5 m
- Maximum piping length:
- 50 m (AOTH65KB / AOTH65KR class)
- 75 m (AOTH72KR / AOTH90KR class)
- Maximum height difference (indoor ↔ outdoor): 30 m
- Always insulate both liquid and gas lines. Increase insulation thickness in high humidity environments.
6) Electrical requirements
6.1 Outdoor unit (AOTH) power supply
- Confirm nameplate supply and local wiring rules before commencing.
| Outdoor model | Supply | Breaker capacity (guide) | Power supply cable (minimum) |
|---|---|---|---|
| AOTH65KBTA | 220–240V ~ 1Φ 50Hz | 25A | 4.0 mm² (Type 60245 IEC 57 or local equivalent) |
| AOTH65KRTA | 380–415V ~ 3Φ 50Hz | 16A | 4.0 mm² (Type 60245 IEC 57 or local equivalent) |
| AOTH72KRTA | 380–415V ~ 3Φ 50Hz | 16A | 4.0 mm² (Type 60245 IEC 57 or local equivalent) |
| AOTH90KRTA | 380–415V ~ 3Φ 50Hz | 20A | 4.0 mm² (Type 60245 IEC 57 or local equivalent) |
6.2 Indoor-to-outdoor connection cable
- Conductor size: minimum 1.5 mm², Type 60245 IEC 57 (or local equivalent).
- Core requirement: 3 cores + Ground (Earth) (connect to terminals 1–2–3 + earth as labelled).
- Limit voltage drop to less than 2%; increase conductor size if required.
- Do not connect AC supply to communication/transmission terminals.
6.3 Wired remote controller cable (if fitted)
- Use shielded cable and route away from mains wiring where practicable.
| Controller type | Conductor size | Remarks |
|---|---|---|
| 2-wire type | 0.33 to 1.25 mm² | Non-polar 2-core (twisted pair recommended) |
| 3-wire type | 0.33 mm² | Polar 3-core |
7) Outdoor unit installation (AOTH)
7.1 Location and mounting
- Install on a base that can withstand weight and vibration; use anchor bolts and appropriate anti-vibration measures.
- Do not install where combustible gas may accumulate or in corrosive environments.
- Provide appropriate service clearances and airflow clearances in accordance with the installation manual.
- Secure appropriately for local wind/weather conditions.
7.2 Drain installation (outdoor)
- Heating operation produces drain water; connect to suitable drain where applicable.
- Where freezing is possible, manage drain paths to prevent ice-related hazards.
8) Indoor unit installation (ARTH – duct type)
8.1 Site selection (minimum requirements)
- Install level and on a structure capable of supporting the unit weight and vibration.
- Provide service access for electrical cover, filter access, and drain maintenance.
- Confirm adequate space for duct connections and condensate drainage fall.
8.2 Condensate drain – key requirements
- Install drain hose with a continuous downward gradient of 1/100 or more; avoid rises.
- Do not create a water trap; avoid kinks, compression, or upward loops.
- Insulate drain hose in high humidity spaces to prevent external condensation.
- Confirm drainage by test-filling or during commissioning; rectify any leakage before ceiling closure.
8.3 Indoor wiring (ARTH) – field notes
- Use the specified connection cable type and secure with the cord clamp.
- Do not splice/extend wiring in a manner that can loosen or overheat; follow local code.
- Use ring terminals where specified; ensure correct screw torque:
| Terminal screw | Tightening torque |
|---|---|
| M4 | 1.2 to 1.8 N·m |
| M5 | 2.0 to 3.0 N·m |
9) Pressure test, evacuation, commissioning
9.1 Flare work – tightening torques (system)
| Outside diameter | Flare nut tightening torque |
|---|---|
| 6.35 mm (1/4") | 16 to 18 N·m |
| 9.52 mm (3/8") | 32 to 42 N·m |
| 12.70 mm (1/2") | 49 to 61 N·m |
| 15.88 mm (5/8") | 63 to 75 N·m |
| 19.05 mm (3/4") | 90 to 110 N·m |
9.2 Nitrogen pressure test (outdoor reference)
- With valves closed, pressurise with nitrogen to 4.15 MPa.
- Check all flare joints and brazed points; rectify any leakage and retest.
9.3 Vacuum evacuation
- Evacuate to -0.1 MPa (-76 cmHg).
- When -0.1 MPa is reached, operate the vacuum pump for at least 60 minutes.
9.4 Service valve / port cap torques (outdoor reference)
| Cap / Port | Applicable size | Tightening torque |
|---|---|---|
| Blank cap | 6.35 mm (1/4"), 9.52 mm (3/8") | 20 to 25 N·m |
| Blank cap | 12.70 mm (1/2") | 28 to 32 N·m |
| Blank cap | 15.88 mm (5/8") | 30 to 35 N·m |
| Blank cap | 19.05 mm (3/4") | 35 to 40 N·m |
| Charging port cap | R32 | 12.5 to 16.0 N·m |
10) Additional refrigerant charging (AOTH)
- Only charge R32 by weight using electronic scales.
- Charge after evacuation and confirming the system is leak-free.
- Do not reuse recovered refrigerant.
Additional charge – guide values (beyond pre-charge length)
| Outdoor model group | Pre-charge length | Additional charge rate | Worked examples (additional only) |
|---|---|---|---|
| AOTH65KB / AOTH65KR class | 30 m | 40 g/m | 40 m: +400 g | 50 m: +800 g |
| AOTH72KR / AOTH90KR class | 30 m | 60 g/m | 40 m: +600 g | 50 m: +1200 g | 60 m: +1800 g | 70 m: +2400 g | 75 m: +2700 g |
- Governance: Always confirm maximum allowable total charge per the unit nameplate / latest manufacturer documentation and local code before charging.
11) Wired remote controller (optional) – quick reference
- Wired remote controller types vary (2-wire non-polar vs 3-wire polar). Confirm the controller type before wiring.
- Use shielded cable and keep separation from mains wiring to reduce noise pickup.
- Controller cable sizing guide:
- 2-wire type: 0.33 to 1.25 mm² (non-polar)
- 3-wire type: 0.33 mm² (polar)
12) Test run and handover
12.1 Check items
- Remote controller operation normal
- Airflow/duct operation normal; no abnormal noise or vibration
- Drainage is normal (no indoor water leakage / sweating)
- No refrigerant leakage detected
- All covers fitted and cable clamps secured
12.2 Customer guidance
- Explain operation, setpoints, timers, and controller functions.
- Explain filter maintenance requirements and service access locations.
- Provide applicable operation manuals to the customer/end user.
13) Pump down (forced cooling operation) – Outdoor unit reference
- Use pump down for relocation/disposal refrigerant recovery in accordance with the manufacturer procedure.
- Initiate forced cooling/test run mode per controller guidance (method varies by controller type).
- Close the liquid valve first, then close the gas valve after a short run period, then stop operation.
- Do not proceed if refrigerant is depleted due to damaged piping; confirm leak-free condition first.
14) Error codes (ARTH indoor + AOTH outdoor + UTY-RNRT wall controller)
Important: The manufacturer tables include some errors that may be irrelevant to this specific model combination. Always validate wiring/communications first, then sensors/actuators as per standard diagnostic workflow.
14.1 UTY-RNRT (Wall controller) – Error Information codes
| Error code | Contents |
|---|---|
| CC.1 | Sensor error |
| C2.1 | Transmission PCB error |
| 12.1 | Wired remote controller communication error |
| 12.3 | Number excess of device in wired remote controller system |
| 12.4 | Wired remote controller system start-up error |
| 26.4 | Address duplication in wired remote controller system |
| 26.5 | Address setting error in wired remote controller system |
| 15.4 | Data acquisition error |
14.2 ARTH (Indoor unit) – Lamp flash error code table (X-Y)
Format below is the indoor receiver lamp flash interpretation used in the ARTH installation manual:
- X = OPERATION lamp (green) number of flashes
- Y = TIMER lamp (orange) number of flashes
| Error code (X-Y) | Description |
|---|---|
| 1-1 | Serial communication error |
| 1-2 | Wired remote controller communication error |
| 1-5 | Check run unfinished / Automatic airflow adjustment error |
| 1-6 | Peripheral unit transmission PCB connection error |
| 1-8 | External communication error |
| 2-1 | Unit number or Refrigerant circuit address setting error (simultaneous multi-split type) |
| 2-2 | Indoor unit capacity error |
| 2-3 | Combination error |
| 2-4 | Connection unit number error (indoor secondary unit) – simultaneous multi-split type / Connection unit number error (indoor unit or branch unit) – flexible multi-split type |
| 2-6 | Indoor unit address setting error |
| 2-7 | Primary unit / secondary unit setup error (simultaneous multi-split type) |
| 2-9 | Connection unit number error in wired remote controller system |
| 3-1 | Power supply interruption error |
| 3-2 | Indoor unit PCB model information error |
| 3-3 | Indoor unit motor electricity consumption detection error |
| 3-5 | Manual auto switch error |
| 3-9 | Indoor unit power supply error for fan motor |
| 3-10 | Indoor unit communication circuit (wired remote controller) error |
| 4-1 | Room temp. sensor error |
| 4-2 | Indoor unit heat exchanger middle temp. sensor error |
| 4-4 | Occupancy sensor error |
| 5-1 | Indoor unit fan motor error |
| 5-3 | Drain pump error |
| 5-7 | Damper error |
| 5-15 | Indoor unit error |
| 6-1 | Outdoor unit reverse/missing phase and wiring error |
| 6-2 | Outdoor unit main PCB model information error or communication error |
| 6-3 | Inverter error |
| 6-4 | Active filter error / PFC circuit error |
| 6-5 | Trip terminal L error / IPM temp. error |
| 6-8 | Outdoor unit rush current limiting resister temp. rise error |
| 6-10 | Display PCB microcomputers communication error |
| 7-1 | Discharge temp. sensor error |
| 7-2 | Compressor temp. sensor error |
| 7-3 | Outdoor unit Heat Ex. liquid temp. sensor error |
| 7-4 | Outdoor temp. sensor error |
| 7-5 | Suction gas temp. sensor error |
| 7-6 | 2-way valve temp. sensor error / 3-way valve temp. sensor error |
| 7-7 | Heat sink temp. sensor error |
| 8-2 | Sub-cool Heat Ex. gas inlet temp. sensor error / Sub-cool Heat Ex. gas outlet temp. sensor error |
| 8-3 | Liquid pipe temp. sensor error |
| 8-4 | Current sensor error |
| 8-6 | Discharge pressure sensor error / Suction pressure sensor error / High pressure switch error |
| 9-4 | Trip detection |
| 9-5 | Compressor rotor position detection error (permanent stop) |
| 9-7 | Outdoor unit fan motor 1 error |
| 9-8 | Outdoor unit fan motor 2 error |
| 9-9 | 4-way valve error |
| 9-10 | Coil (expansion valve) error |
| 10-1 | Discharge temp. error |
| 10-3 | Compressor temp. error |
| 10-4 | High pressure error |
| 10-5 | Low pressure error |
| 10-11 | Heat sink temp. error |
| 13-2 | Branch boxes error (flexible multi-split type) |
14.3 AOTH (Outdoor unit) – LED display error code check table (condensed)
Outdoor LED interpretation aligns to the AOTH installation manual “10.2 Error code check table”. Pattern below summarises the LED display state at fault:
- Power/Mode = blink count
- L1 = PUMP DOWN LED (blink count)
- L2 = LOW NOISE LED (blink count)
- L3–L6 = ON/OFF indicators per manual table
| LED pattern | Description | Remark |
|---|---|---|
| Power/Mode: Blink 2 L1: Blink 1 L2: Blink 1 L3: OFF L4: OFF L5: ON L6: ON | Serial communication error | Serial forward transmission error immediately after operation |
| Power/Mode: Blink 2 L1: Blink 1 L2: Blink 1 L3: OFF L4: ON L5: OFF L6: OFF | Serial communication error | Serial forward transmission error during operation |
| Power/Mode: Blink 2 L1: Blink 2 L2: Blink 2 L3: OFF L4: OFF L5: OFF L6: ON | Indoor unit capacity error | Indoor unit capacity error |
| Power/Mode: Blink 2 L1: Blink 2 L2: Blink 3 L3: OFF L4: OFF L5: OFF L6: ON | Incompatible series connection error | Connection forbidden (series error) |
| Power/Mode: Blink 2 L1: Blink 5 L2: Blink 15 L3: OFF L4: OFF L5: OFF L6: ON | Indoor unit error | Indoor unit error |
| Power/Mode: Blink 2 L1: Blink 6 L2: Blink 1 L3: OFF L4: ON L5: OFF L6: ON | Outdoor unit power supply error | Outdoor unit reverse/missing phase and wiring error |
| Power/Mode: Blink 2 L1: Blink 6 L2: Blink 2 L3: OFF L4: OFF L5: OFF L6: ON | Outdoor unit main PCB error | Outdoor unit PCB model information error |
| Power/Mode: Blink 2 L1: Blink 6 L2: Blink 3 L3: OFF L4: OFF L5: OFF L6: ON | Inverter PCB error | Inverter error |
| Power/Mode: Blink 2 L1: Blink 6 L2: Blink 5 L3: OFF L4: OFF L5: OFF L6: ON | IPM error | Temperature error |
| Power/Mode: Blink 2 L1: Blink 6 L2: Blink 5 L3: OFF L4: OFF L5: ON L6: ON | IPM error | Trip terminal L error |
| Power/Mode: Blink 2 L1: Blink 7 L2: Blink 1 L3: OFF L4: OFF L5: OFF L6: ON | Discharge temp. sensor error | Discharge temp. sensor 1 error |
| Power/Mode: Blink 2 L1: Blink 7 L2: Blink 2 L3: OFF L4: OFF L5: OFF L6: ON | Compressor temp. sensor error | Compressor temp. sensor 1 error |
| Power/Mode: Blink 2 L1: Blink 7 L2: Blink 3 L3: OFF L4: OFF L5: ON L6: OFF | Outdoor unit Heat Ex. sensor error | Heat Ex. center temp. sensor error |
| Power/Mode: Blink 2 L1: Blink 7 L2: Blink 3 L3: OFF L4: OFF L5: ON L6: ON | Outdoor unit Heat Ex. sensor error | Outdoor unit Heat Ex. liquid temp. sensor error |
| Power/Mode: Blink 2 L1: Blink 7 L2: Blink 4 L3: OFF L4: OFF L5: OFF L6: ON | Outdoor temp. sensor error | Outdoor temp. sensor error |
| Power/Mode: Blink 2 L1: Blink 7 L2: Blink 7 L3: OFF L4: OFF L5: OFF L6: ON | Heat sink temp. sensor error | Heat sink temp. sensor error |
| Power/Mode: Blink 2 L1: Blink 8 L2: Blink 4 L3: OFF L4: OFF L5: OFF L6: ON | Current sensor error | Current sensor 1 error (stoppage permanently) |
| Power/Mode: Blink 2 L1: Blink 8 L2: Blink 6 L3: OFF L4: ON L5: OFF L6: OFF | Pressure sensor error | High pressure switch 1 error |
| Power/Mode: Blink 2 L1: Blink 8 L2: Blink 6 L3: OFF L4: ON L5: ON L6: OFF | Pressure sensor error | Pressure sensor error |
| Power/Mode: Blink 2 L1: Blink 9 L2: Blink 4 L3: OFF L4: OFF L5: OFF L6: ON | Trip detection | Trip detection |
| Power/Mode: Blink 2 L1: Blink 9 L2: Blink 5 L3: OFF L4: OFF L5: OFF L6: ON | Compressor motor control error | Rotor position detection error (stoppage permanently) |
| Power/Mode: Blink 2 L1: Blink 9 L2: Blink 7 L3: OFF L4: OFF L5: ON L6: OFF | Outdoor unit fan motor 1 error | Fan motor 1 error (stoppage permanently) |
| Power/Mode: Blink 2 L1: Blink 9 L2: Blink 8 L3: OFF L4: OFF L5: ON L6: OFF | Outdoor unit fan motor 2 error | Fan motor 2 error (stoppage permanently) |
| Power/Mode: Blink 2 L1: Blink 9 L2: Blink 9 L3: OFF L4: OFF L5: OFF L6: ON | 4-way valve error | 4-way valve error |
| Power/Mode: Blink 2 L1: Blink 10 L2: Blink 1 L3: OFF L4: OFF L5: OFF L6: ON | Discharge temp. 1 error | Discharge temp. 1 error |
| Power/Mode: Blink 2 L1: Blink 10 L2: Blink 3 L3: OFF L4: OFF L5: OFF L6: ON | Compressor temp. error | Compressor 1 temp. error |
| Power/Mode: Blink 2 L1: Blink 10 L2: Blink 5 L3: OFF L4: OFF L5: OFF L6: ON | Pressure error 2 | Low pressure error |
| Power/Mode: Blink 2 L1: Blink 10 L2: Blink 11 L3: OFF L4: OFF L5: ON L6: ON | Heat sink temp. error | Heat sink temp. error |
Operational note: If using UTY-RNRT, the controller “Error Information” screen may show a 2-digit error code. For indoor/outdoor functional faults, use the applicable ARTH/AOTH tables above and then proceed with standard diagnostics (power supply / phase / comms first, then sensors, then actuators).
Document control: This Solution article is intended as a consolidated, text-only field reference for KBTA/KRTA series installation. Always comply with local regulations and refer to the latest manufacturer documentation for detailed diagrams, part numbers, and regional variations.