Installation Manual (View Online) – KHTA / KHTB / KCTA / KBTA / KRTA Series (R32): Ducted Indoor Units + Outdoor Units + UTY-RNRT Wired Controller

Applies to the following models:
Indoor (Ducted): ARTH24KHTA, ARTH30KHTA, ARTH36KHTA, ARTH45KHTA, ARTH54KHTA, ARTH60KHTA, ARTH60KHTB
Outdoor (Single type): AOTH24KCTA, AOTH30KCTA, AOTH36KCTA, AOTH45KCTA, AOTH54KCTA, AOTH60KCTA, AOTH60KBTA, AOTH60KRTA
Wired Controller: UTY-RNRT
Refrigerant: R32
Audience: Authorised service personnel / professional installers

Contents

1) Safety and compliance

  • Installation and servicing must be completed by qualified and experienced personnel only.
  • Do not energise the system until all installation work is complete and all covers are fitted.
  • After isolating power, wait before touching electrical components (observe manufacturer discharge guidance).
  • If refrigerant leakage occurs during works: ventilate immediately and remove ignition sources. Do not use open flames.
  • Use vacuum pump evacuation. Do not purge air with refrigerant.
  • Ensure correct grounding/earthing and earth leakage protection in accordance with local regulations.
  • Keep ductwork and surrounding areas free of ignition sources (no hot surfaces, open flames, or arcing/sparking devices within ducts or return air paths).

2) R32 refrigerant requirements

  • R32 is classified as a flammable refrigerant. Apply appropriate controls: ventilation, ignition source exclusion, and compliant leak checking.
  • Use only R32/R410A rated tools, hoses, gauges, and piping materials.
  • Charging port thread for R32/R410A is 1/2–20 UNF.
  • Prevent moisture/foreign matter from entering refrigerant piping; seal pipe ends during handling and storage.
  • Leak detection methods must be suitable for flammable refrigerants; do not use open flame detection.

2.1 Minimum room area guidance (where applicable)

Minimum room area depends on installation height and the total refrigerant charge (M). If the ducted system conditions more than one room, apply the minimum room area requirement to the smallest room served (where this requirement applies).

Minimum room area by total charge (M):

  • M ≤ 1.842 kg: No minimum room area listed (reference condition).
  • 1.842 kg < M ≤ 2.00 kg: Minimum 4.83 m² (1.8 ≤ H < 2.2 m) OR 3.95 m² (H ≥ 2.2 m).
  • 2.00 kg < M ≤ 2.25 kg: Minimum 5.43 m² (1.8 ≤ H < 2.2 m) OR 4.45 m² (H ≥ 2.2 m).
  • 2.25 kg < M ≤ 2.50 kg: Minimum 6.04 m² (1.8 ≤ H < 2.2 m) OR 4.94 m² (H ≥ 2.2 m).
  • 2.50 kg < M ≤ 2.75 kg: Minimum 7.16 m² (1.8 ≤ H < 2.2 m) OR 5.43 m² (H ≥ 2.2 m).
  • 2.75 kg < M ≤ 3.00 kg: Minimum 8.52 m² (1.8 ≤ H < 2.2 m) OR 5.93 m² (H ≥ 2.2 m).
  • 3.00 kg < M ≤ 3.25 kg: Minimum 9.99 m² (1.8 ≤ H < 2.2 m) OR 6.69 m² (H ≥ 2.2 m).
  • 3.25 kg < M ≤ 3.50 kg: Minimum 11.59 m² (1.8 ≤ H < 2.2 m) OR 7.76 m² (H ≥ 2.2 m).
  • 3.50 kg < M ≤ 3.75 kg: Minimum 13.30 m² (1.8 ≤ H < 2.2 m) OR 8.91 m² (H ≥ 2.2 m).
  • 3.75 kg < M ≤ 4.00 kg: Minimum 15.14 m² (1.8 ≤ H < 2.2 m) OR 10.13 m² (H ≥ 2.2 m).
  • 4.00 kg < M ≤ 4.25 kg: Minimum 17.09 m² (1.8 ≤ H < 2.2 m) OR 11.44 m² (H ≥ 2.2 m).
  • 4.25 kg < M ≤ 4.50 kg: Minimum 19.15 m² (1.8 ≤ H < 2.2 m) OR 12.82 m² (H ≥ 2.2 m).
  • 4.50 kg < M ≤ 4.75 kg: Minimum 21.34 m² (1.8 ≤ H < 2.2 m) OR 14.29 m² (H ≥ 2.2 m).
  • 4.75 kg < M ≤ 5.00 kg: Minimum 23.65 m² (1.8 ≤ H < 2.2 m) OR 15.83 m² (H ≥ 2.2 m).
  • 5.00 kg < M ≤ 5.25 kg: Minimum 26.07 m² (1.8 ≤ H < 2.2 m) OR 17.45 m² (H ≥ 2.2 m).
  • 5.25 kg < M ≤ 5.50 kg: Minimum 28.61 m² (1.8 ≤ H < 2.2 m) OR 19.15 m² (H ≥ 2.2 m).
  • 5.50 kg < M ≤ 5.75 kg: Minimum 31.27 m² (1.8 ≤ H < 2.2 m) OR 20.93 m² (H ≥ 2.2 m).
  • 5.75 kg < M ≤ 6.00 kg: Minimum 34.05 m² (1.8 ≤ H < 2.2 m) OR 22.79 m² (H ≥ 2.2 m).

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 (suitable for flammable refrigerants)
  • Tube cutter, deburr tool, flare tool suitable for R32/R410A, torque wrenches
  • Nitrogen cylinder and regulator for pressure testing
  • Electronic scales for charging
  • Fire extinguisher (dry powder or CO2) available near charging/recovery work area

4) System overview (power, control, commissioning flow)

  • Recommended workflow: Mechanical installation → electrical installation → nitrogen pressure test → vacuum evacuation → open service valves → additional charge (if required) → function settings (static pressure) → test run → handover.
  • Confirm terminal numbering and wiring match at both ends. Route cables to avoid contact with sharp edges and refrigerant piping.
  • Where UTY-RNRT is used, confirm controller wiring, system addressing/grouping, and controller configuration prior to commissioning.
  • Power arrangement: The indoor unit is powered from the outdoor unit. Do not supply separate mains power to the indoor unit unless specifically required by a site-approved design.

5) Refrigerant piping requirements

5.1 Copper pipe requirements (R32/R410A)

  • Use seamless phosphor deoxidised copper.
  • Do not reuse existing piping due to contamination and compatibility risk.
  • Seal pipe ends during handling/storage to prevent moisture ingress.

Minimum copper thickness (annealed copper):

  • Outside diameter 6.35 mm (1/4"): minimum 0.80 mm
  • Outside diameter 9.52 mm (3/8"): minimum 0.80 mm
  • Outside diameter 12.70 mm (1/2"): minimum 0.80 mm
  • Outside diameter 15.88 mm (5/8"): minimum 1.00 mm
  • Outside diameter 19.05 mm (3/4"): minimum 1.20 mm

5.2 Refrigerant pipe sizes by outdoor model (Liquid line / Gas line)

Important: Always insulate both liquid and gas lines. Increase insulation thickness in high humidity environments.

  • AOTH24KCTA: Standard 6.35 mm (1/4") / 12.70 mm (1/2"); Optional 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH30KCTA: Standard 6.35 mm (1/4") / 12.70 mm (1/2"); Optional 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH36KCTA: Standard 6.35 mm (1/4") / 12.70 mm (1/2"); Optional 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH45KCTA: 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH54KCTA: 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH60KCTA: 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH60KBTA: 9.52 mm (3/8") / 15.88 mm (5/8")
  • AOTH60KRTA: 9.52 mm (3/8") / 15.88 mm (5/8")

5.3 Refrigerant piping limits (by outdoor model)

  • All models: Minimum piping length 5 m
  • All models: Maximum height difference (Indoor to Outdoor) 30 m
  • AOTH24KCTA: Maximum piping length 75 m
  • AOTH30KCTA: Maximum piping length 75 m
  • AOTH36KCTA: Maximum piping length 75 m
  • AOTH45KCTA: Maximum piping length 75 m
  • AOTH54KCTA: Maximum piping length 75 m
  • AOTH60KCTA: Maximum piping length 75 m
  • AOTH60KBTA: Maximum piping length 50 m
  • AOTH60KRTA: Maximum piping length 50 m

6) Electrical requirements

6.1 Outdoor unit power supply

  • Voltage rating: Single phase 220–240 V (50 Hz) and Three phase 380–415 V (50 Hz)
  • Operating range: Single phase 198–264 V and Three phase 342–457 V
  • Allowable system impedance: AOTH24KCTA, AOTH30KCTA, AOTH36KCTA = 0.419 Ω; AOTH45KCTA, AOTH54KCTA, AOTH60KCTA, AOTH60KBTA, AOTH60KRTA = 0.428 Ω

6.2 Power supply cable (minimum requirements)

  • Single phase outdoor units (where applicable): Minimum 4 mm², Type 60245 IEC 66, 2-core + Earth
  • Three phase outdoor units (where applicable): Minimum 2.5 mm², Type 60245 IEC 57, 4-core + Earth

6.3 Breaker and earth leakage breaker (reference values)

  • AOTH24KCTA: Breaker capacity 25 A; Earth leakage breaker 30 mA
  • AOTH30KCTA: Breaker capacity 25 A; Earth leakage breaker 30 mA
  • AOTH36KCTA: Breaker capacity 25 A; Earth leakage breaker 30 mA
  • AOTH45KCTA: Breaker capacity 32 A; Earth leakage breaker 30 mA
  • AOTH54KCTA: Breaker capacity 32 A; Earth leakage breaker 30 mA
  • AOTH60KCTA: Breaker capacity 32 A; Earth leakage breaker 30 mA
  • AOTH60KBTA: Breaker capacity 16 A; Earth leakage breaker 30 mA
  • AOTH60KRTA: Breaker capacity 16 A; Earth leakage breaker 30 mA

6.4 Disconnect device

  • Install an isolator/disconnect device nearby the units with a contact gap of at least 3 mm in all poles, in accordance with local requirements.

6.5 Indoor-to-outdoor connection cable (indoor is powered from outdoor)

  • Indoor power source: The indoor unit is powered from the outdoor unit. Do not connect a separate mains power supply to the indoor unit.
  • Connection cable: Minimum 1.5 mm², Type 60245 IEC 57, 3-core + Earth (terminal assignment per unit)
  • Maximum length: 40 m (maintain voltage drop < 2%; increase conductor size where required)
  • Do not connect AC supply to transmission terminals.

6.6 UTY-RNRT wired controller cable (reference)

  • Cable type: 2-core, non-polar, 0.33 to 1.25 mm² (use sheathed cable and comply with local requirements)
  • Maximum length: Up to 500 m (subject to site conditions and noise environment)
  • Route controller cabling separately from mains power cabling to reduce noise interference.

7) Outdoor unit installation

7.1 Location and mounting

  • Install on a base that can withstand the unit weight and vibration. Use anchor bolts and anti-vibration measures as required.
  • Maintain required clearances for airflow and service access. Prevent discharge air recirculation.
  • Do not install where combustible gas may accumulate or in corrosive environments.
  • Secure appropriately for local wind/weather conditions.

7.2 Drain considerations (outdoor)

  • Heating operation produces drain water; route to a suitable drain point where applicable.
  • In freezing climates, implement appropriate freeze protection measures per local best practice.

8) Indoor unit installation

8.1 Site selection and serviceability

  • Install in a location that supports the indoor unit mass and minimises vibration transmission.
  • Ensure ductwork, filter access, and condensate drain access remain serviceable after installation.
  • Ensure access for electrical servicing and refrigerant piping connections.

8.2 Ductwork and airflow management

  • Confirm duct system design external static pressure aligns with unit capability and the intended function setting.
  • Seal duct joints to prevent leakage and performance degradation.
  • Confirm return air path and filter arrangement prevents debris ingress to the fan and coil.

8.3 Condensate drain

  • Provide correct fall and trapping per local best practice to prevent blow-off and odours.
  • Insulate condensate drain line where sweating may occur.
  • Water-test drainage before ceiling closure and prior to handover.

9) Pressure test, evacuation, commissioning

9.1 Flare tightening torques

Use a torque wrench. Tighten to the following flare nut torque values:

  • 6.35 mm (1/4") flare nut: 16–18 N·m
  • 9.52 mm (3/8") flare nut: 32–42 N·m
  • 12.70 mm (1/2") flare nut: 49–61 N·m
  • 15.88 mm (5/8") flare nut: 63–75 N·m
  • 19.05 mm (3/4") flare nut: 90–110 N·m

9.2 Nitrogen pressure test (air tightness test)

  • Perform the air tightness test using nitrogen while outdoor unit service valves are closed.
  • Use the test pressure indicated on the outdoor unit nameplate and confirm all joints are leak-free before evacuation.
  • If leakage is detected, rectify and re-test before proceeding.

9.3 Vacuum evacuation

  • Evacuate to –0.1 MPa (–76 cmHg).
  • When –0.1 MPa is reached, continue vacuum pump operation for at least 60 minutes.
  • After evacuation, disconnect hoses, then open service valves fully and refit caps to the specified torque.

9.4 Service valve and charging port cap torques

  • Blank cap for 6.35 mm (1/4") and 9.52 mm (3/8"): 20–25 N·m
  • Blank cap for 12.70 mm (1/2"): 28–32 N·m
  • Blank cap for 15.88 mm (5/8"): 30–35 N·m
  • Blank cap for 19.05 mm (3/4"): 35–40 N·m
  • Charging port cap (R32/R410A): 12.5–16 N·m

10) Additional refrigerant charging

  • Factory charge: Refer to the outdoor unit rating label (varies by model).
  • Pre-charge length: 30 m
  • If the total refrigerant piping length exceeds 30 m, additional refrigerant is required.
  • Record factory charge, additional charge, and total charge on the outdoor unit refrigerant label.

10.1 Additional charge rates by model and installed pipe size

AOTH24KCTA, AOTH30KCTA, AOTH36KCTA:

  • If installed pipe size is 6.35 mm (1/4") liquid and 12.70 mm (1/2") gas: add 20 g per metre beyond 30 m.
    Formula: Additional charge (g) = (Total pipe length in m – 30) × 20
  • If installed pipe size is 9.52 mm (3/8") liquid and 15.88 mm (5/8") gas: add 40 g per metre beyond 30 m.
    Formula: Additional charge (g) = (Total pipe length in m – 30) × 40

AOTH45KCTA, AOTH54KCTA, AOTH60KCTA:

  • Installed pipe size is 9.52 mm (3/8") liquid and 15.88 mm (5/8") gas: add 40 g per metre beyond 30 m.
    Formula: Additional charge (g) = (Total pipe length in m – 30) × 40

AOTH60KBTA, AOTH60KRTA:

  • Installed pipe size is 9.52 mm (3/8") liquid and 15.88 mm (5/8") gas: add 40 g per metre beyond 30 m.
    Formula: Additional charge (g) = (Total pipe length in m – 30) × 40

10.2 Worked examples (for clarity)

  • AOTH24KCTA with 6.35/12.70 mm piping: If total length is 40 m → (40 – 30) × 20 = 200 g additional charge.
  • AOTH24KCTA with 6.35/12.70 mm piping: If total length is 50 m → (50 – 30) × 20 = 400 g additional charge.
  • AOTH24KCTA with 9.52/15.88 mm piping: If total length is 40 m → (40 – 30) × 40 = 400 g additional charge.
  • AOTH24KCTA with 9.52/15.88 mm piping: If total length is 60 m → (60 – 30) × 40 = 1200 g additional charge.
  • AOTH45KCTA with 9.52/15.88 mm piping: If total length is 75 m → (75 – 30) × 40 = 1800 g additional charge.
  • AOTH60KRTA with 9.52/15.88 mm piping: If total length is 50 m → (50 – 30) × 40 = 800 g additional charge.

10.3 Maximum total refrigerant charge limit (AOTH24KCTA / AOTH30KCTA / AOTH36KCTA)

  • AOTH24KCTA: Maximum total charge 2700 g
  • AOTH30KCTA: Maximum total charge 3900 g
  • AOTH36KCTA: Maximum total charge 4300 g

11) Indoor function settings

  • Objective: Align indoor fan operation to the duct system’s design external static pressure.
  • Factory setting reference: 100 Pa.
  • Complete ducting and filters before setting static pressure. Incomplete ductwork may result in incorrect airflow setup.
  • Function settings are performed via the controller/service procedure (UTY-RNRT environment).

11.1 Static pressure setting (Function number 26) for ARTH24KHTA, ARTH30KHTA, ARTH36KHTA

Function number 26 setting values:

  • Function 26 value 06 = 60 Pa
  • Function 26 value 07 = 70 Pa
  • Function 26 value 08 = 80 Pa
  • Function 26 value 09 = 90 Pa
  • Function 26 value 10 = 100 Pa (factory)
  • Function 26 value 11 = 110 Pa
  • Function 26 value 12 = 120 Pa
  • Function 26 value 13 = 130 Pa
  • Function 26 value 14 = 140 Pa
  • Function 26 value 15 = 150 Pa
  • Function 26 value 16 = 160 Pa
  • Function 26 value 32 = Automatic airflow adjustment

11.2 Static pressure setting (Function number 26) for ARTH45KHTA, ARTH54KHTA, ARTH60KHTA, ARTH60KHTB

Function number 26 setting values:

  • Function 26 value 00 = 0 Pa
  • Function 26 value 01 = 10 Pa
  • Function 26 value 02 = 20 Pa
  • Function 26 value 03 = 30 Pa
  • Function 26 value 04 = 40 Pa
  • Function 26 value 05 = 50 Pa
  • Function 26 value 06 = 60 Pa
  • Function 26 value 07 = 70 Pa
  • Function 26 value 08 = 80 Pa
  • Function 26 value 09 = 90 Pa
  • Function 26 value 10 = 100 Pa (factory)
  • Function 26 value 11 = 110 Pa
  • Function 26 value 12 = 120 Pa
  • Function 26 value 13 = 130 Pa
  • Function 26 value 14 = 140 Pa
  • Function 26 value 15 = 150 Pa
  • Function 26 value 16 = 160 Pa
  • Function 26 value 17 = 170 Pa
  • Function 26 value 18 = 180 Pa
  • Function 26 value 19 = 190 Pa
  • Function 26 value 20 = 200 Pa
  • Function 26 value 21 = 210 Pa
  • Function 26 value 22 = 220 Pa
  • Function 26 value 23 = 230 Pa
  • Function 26 value 24 = 240 Pa
  • Function 26 value 25 = 250 Pa
  • Function 26 value 26 = 260 Pa
  • Function 26 value 27 = 270 Pa
  • Function 26 value 28 = 280 Pa
  • Function 26 value 29 = 290 Pa
  • Function 26 value 30 = 300 Pa
  • Function 26 value 31 = 310 Pa
  • Function 26 value 32 = Automatic airflow adjustment

11.3 Operational guidance

  • Manual setting: Select the required Pa value when duct design external static pressure is known.
  • Automatic airflow adjustment: Use when commissioning requires automated fan calibration. Ensure duct system, filters, and zones are complete and stable before initiation.
  • After changes, validate airflow, noise profile, and temperature performance under normal load conditions.

12) Test run and handover

12.1 Commissioning check items

  • UTY-RNRT controller operation and display status normal
  • Indoor fan operation stable with no abnormal ramping
  • Target airflow achieved and duct system balanced
  • Condensate drainage normal with no water leakage
  • No abnormal noise or vibration
  • No refrigerant leakage detected

12.2 Handover expectations

  • Explain controller operation, temperature settings, and schedules (where applicable).
  • Explain filter access, cleaning intervals, and service requirements.
  • Confirm any BMS interface, external interlocks, or safety shutdowns (if installed).

13) Pump down (forced cooling operation)

  • Purpose: Store refrigerant in the outdoor unit to support relocation/service work (apply full R32 safety and recovery requirements).
  • Pre-conditions: Confirm the refrigerant circuit is leak-free. Do not proceed if refrigerant is depleted due to damaged piping.

13.1 Pump down procedure

  1. Connect gauge manifold to the outdoor service port and confirm normal operation readiness.
  2. Start forced cooling operation (test run / forced operation method as applicable for the installed outdoor unit/controller).
  3. Fully close the 2-way valve (liquid valve).
  4. Continue forced cooling while monitoring pressure; avoid operating into deep vacuum.
  5. Fully close the 3-way valve (gas valve).
  6. Stop operation, isolate power, and proceed with recovery/pipework disconnection as required.

Control note: Forced cooling operation method varies by model/controller environment. Use the outdoor unit forced operation function and/or the controller test run function as applicable.

14) Error codes (indoor/outdoor consolidated)

Error codes may be displayed on the UTY-RNRT controller, shown on outdoor unit display/LED, or indicated via indoor LED blink patterns where applicable. Capture the displayed code and apply a structured diagnostic workflow (power, wiring, communication, sensors, refrigerant circuit, and inverter components).

14.1 How to check errors

  • UTY-RNRT wired controller: Navigate to Status → Error Information to view current/previous error information.
  • Outdoor unit: Use the outdoor display/error retrieval method on the control PCB/display. Record the code prior to power cycling.
  • Indoor unit: Use the controller display (preferred) and verify indoor indicators where applicable.

14.2 Consolidated error codes (each code on one line)

  • 11 – Serial communication error
  • 12 – Wired remote controller communication error
  • 15 – Check run unfinished / automatic airflow adjustment error
  • 16 – Peripheral unit transmission PCB connection error
  • 18 – External communication error
  • 21 – Unit number / address setting error (system dependent)
  • 22 – Indoor unit capacity error
  • 23 – Combination error
  • 24 – Connection unit number error (system dependent)
  • 26 – Indoor unit address setting error
  • 27 – Primary/secondary unit setup error (system dependent)
  • 29 – Connection unit number error in wired remote controller system
  • 31 – Power supply interruption error
  • 32 – Indoor unit PCB model information error
  • 33 – Indoor unit motor electricity consumption detection error
  • 35 – Manual auto switch error
  • 39 – Indoor unit power supply error for fan motor
  • 3A – Indoor unit communication circuit (wired remote controller) error
  • 41 – Room temperature sensor error
  • 42 – Indoor unit heat exchanger middle temperature sensor error
  • 44 – Occupancy sensor error
  • 51 – Indoor unit fan motor error
  • 53 – Drain pump error
  • 57 – Damper error
  • 59 – Indoor unit fan motor 2 error
  • 5U – Indoor unit error
  • 61 – Outdoor unit reverse/missing phase and wiring error
  • 62 – Outdoor unit main PCB model information error / communication error
  • 63 – Inverter error
  • 64 – Active filter error / PFC circuit error
  • 65 – Trip terminal / IPM temperature error
  • 68 – Rush current limiting resistor temperature rise error
  • 6A – Display PCB microcomputer communication error
  • 71 – Discharge temperature sensor error
  • 72 – Compressor temperature sensor error
  • 73 – Outdoor heat exchanger liquid temperature sensor error
  • 74 – Outdoor temperature sensor error
  • 75 – Suction gas temperature sensor error
  • 76 – 2-way / 3-way valve temperature sensor error
  • 77 – Heat sink temperature sensor error
  • 82 – Sub-cool heat exchanger sensor error
  • 83 – Liquid pipe temperature sensor error
  • 84 – Current sensor error
  • 86 – Pressure sensor / high pressure switch error
  • 94 – Trip detection
  • 95 – Compressor rotor position detection error (permanent stop)
  • 97 – Outdoor unit fan motor 1 error
  • 98 – Outdoor unit fan motor 2 error
  • 99 – 4-way valve error
  • 9A – Expansion valve (coil) error
  • A1 – Discharge temperature error
  • A3 – Compressor temperature error
  • A4 – High pressure error
  • A5 – Low pressure error
  • AC – Heat sink temperature error
  • J2 – Branch boxes error (system dependent)

15) UTY-RNRT specific error displays

These displays are specific to UTY-RNRT wired controller conditions (in addition to the consolidated system error codes above). Each display is shown on one line for reliable chatbot parsing.

  • CC.1 – Sensor error (wired remote controller side)
  • C2.1 – Transmission PCB error
  • 12.1 – Wired remote controller communication error
  • 12.3 – Communication circuit error (wired remote controller)
  • 12.4 – Indoor unit communication circuit error (wired remote controller)
  • 26.4 – Wired remote controller unit number or refrigerant circuit address setting error
  • 26.5 – Indoor unit address setting error
  • 15.4 – Data acquisition error

Document control: This Solution article is a consolidated, text-oriented field reference for the models listed above. Apply local regulatory requirements and site-specific engineering decisions for final installation compliance.