Installation Manual (View Online) – KMTD Series (R32): Indoor ASTH09/12/18/22/24KMTD + Outdoor AOTH18/22/24KMTD
Applies to:
Indoor (Wall-Mounted): ASTH09KMTD / ASTH12KMTD / ASTH18KMTD / ASTH22KMTD / ASTH24KMTD
Outdoor: AOTH18KMTD / AOTH22KMTD / AOTH24KMTD
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.
- After isolating power, wait before touching electrical components (observe manufacturer discharge time guidance).
- If refrigerant leakage occurs: 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 operates at higher pressures than legacy refrigerants; use R32/R410A-rated tools, hoses and materials only.
- Charging port thread for R32/R410A: 1/2–20 UNF.
- Prevent moisture/foreign matter entering piping; seal pipe ends during storage/handling.
- Leak detection must be suitable for flammable refrigerants; never use open flame methods.
- High-pressure gauge manifold suitable for R32/R410A
- R32/R410A charging hoses
- Vacuum pump and 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 (power + interconnect)
- 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 and route cables to avoid contact with refrigerant piping.
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.
| 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 (ASTH indoor unit connection sizes)
| Indoor model group | Gas pipe size (thickness) | Liquid pipe size (thickness) |
|---|
| ASTH09 / ASTH12 | Ø 9.52 mm (0.80 mm) | Ø 6.35 mm (0.80 mm) |
| ASTH18 / ASTH22 / ASTH24 | Ø 12.70 mm (0.80 mm) | Ø 6.35 mm (0.80 mm) |
5.3 Allowable piping length (Outdoor unit reference)
- Maximum piping length: 30 m
- If the units are further apart than the maximum pipe length, correct operation cannot be guaranteed.
6) Electrical requirements
6.1 Outdoor unit (AOTH) power supply
- Power supply: 220–240V ~ 50Hz
- Operating range (supply voltage): 198 to 264 V
- Power supply cable: minimum 2.5 mm², Type 60245 IEC 57, 2 wire + Ground (Earth) (select per local code)
- Breaker / earth leakage protection (typical by model):
| Outdoor model | Breaker capacity | Earth leakage breaker |
|---|
| AOTH18 | 16 A | 30 mA |
| AOTH22 / AOTH24 | 20 A | 30 mA |
6.2 Indoor-to-outdoor connection cable (ASTH)
- Connection cable: minimum 1.5 mm², Type 60245 IEC 57, 3 wire + Ground (Earth)
- Limit voltage drop to less than 2%; increase conductor size if required.
7) Outdoor unit installation (AOTH)
7.1 Location and mounting
- Install on a base that can withstand weight and vibration; install horizontally.
- Do not install where combustible gas may accumulate or in corrosive environments.
- Provide adequate service clearances for airflow and maintenance access.
7.2 Outdoor drain notes
- If outdoor temperature is 0°C or less, do not use accessory drain pipe (freeze risk).
- Heating operation produces drain water; connect to a suitable drain route where applicable.
8) Indoor unit installation (ASTH)
8.1 Site selection (minimum requirements)
- Install level on a strong wall not subject to vibration.
- Ensure inlet/outlet are unobstructed and airflow reaches the room.
- Install at least 1 m away from TV/radio to reduce interference.
- Install height from floor: more than 1.8 m.
- Allow service access for filter removal and maintenance.
8.2 Wall hole and bracket (summary)
- Wall hole diameter: 65 mm
- Use a wall pipe where required; secure the wall hook bracket level and firmly.
9) Pressure test, evacuation, commissioning
9.1 Flare work – tightening torques
| Pipe size | Outside diameter | Flare nut tightening torque |
|---|
| 1/4" | 6.35 mm | 16–18 N·m (160–180 kgf·cm) |
| 3/8" | 9.52 mm | 32–42 N·m (320–420 kgf·cm) |
| 1/2" | 12.70 mm | 49–61 N·m (490–610 kgf·cm) |
| 5/8" | 15.88 mm | 63–75 N·m (630–750 kgf·cm) |
| 3/4" | 19.05 mm | 90–110 N·m (900–1100 kgf·cm) |
9.2 Nitrogen pressure test (outdoor reference)
- With service valves closed, pressurise with nitrogen to 4.15 MPa and leak-check all joints.
9.3 Vacuum evacuation
- Evacuate to -0.1 MPa (-76 cmHg) and run vacuum pump for at least 15 minutes.
- Open service valves after evacuation and refit caps to specified torques.
9.4 Service valve / port cap torques (outdoor reference)
| Cap / Port | Applicable sizes | Tightening torque |
|---|
| Blank cap | 1/4", 3/8" | 20–25 N·m |
| Blank cap | 1/2" | 28–32 N·m |
| Blank cap | 5/8" | 30–35 N·m |
| Blank cap | 3/4" | 35–40 N·m |
| Charging port cap | R32/R410A | 12.5–16 N·m |
10) Additional refrigerant charging (Outdoor unit AOTH)
- Refrigerant suitable for a piping length of 15 m is factory charged.
- When piping exceeds 15 m, additional charge is required.
- Charging guideline: 20 g/m beyond 15 m (up to maximum piping length).
| Pipe length | 15 m | 20 m | 25 m | 30 m | Rate |
|---|
| Additional refrigerant | None | +100 g | +200 g | +300 g | 20 g/m |
- Maximum total refrigerant charge (system): 1,570 g (1,270 g + 300 g)
- Complete the refrigerant charge label on the outdoor unit: factory charge, additional charge, total charge.
11) Indoor function settings (ASTH)
- Enter function setting mode per wireless remote procedure (per manual).
- After completing function settings, disconnect power and reconnect. Wait 30 seconds or more before reconnecting power.
Common function items (ASTH reference)
- 11 Filter sign interval: 400h (00) / 1000h (01) / 200h (02) / No indication (03 – factory setting)
- 30 / 31 Room temperature control (indoor sensor): cooling/heating correction selections (factory setting = standard)
- 40 Auto restart: Enable (00 – factory setting) / Disable (01)
- 42 Room temperature sensor switching (wired remote only): Indoor unit (00 – factory) / Both (01)
- 44 Remote controller custom code: A (00 – factory) / B (01) / C (02) / D (03)
- 46 External input control: Operation/Stop mode 1 (00 – factory) / Forced stop (02) / Operation/Stop mode 2 (03)
- 49 Indoor unit fan control for energy saving (cooling): Disable (00) / Enable (01) / Remote controller (02 – factory)
- 60 External output terminal function: Operation status (00 – factory) / Error status (09) / Indoor fan operation status (10)
12) Test run and handover
12.1 Check items
- Remote controller operation and indicator lamps normal
- Airflow and louvers operate normally
- Drainage is normal (no indoor water leakage)
- No abnormal noise or vibration
- No refrigerant leakage detected
12.2 Test run methods (ASTH reference)
- Wait at least 1 minute after connecting power before starting test run.
- Indoor unit button method: press and hold indoor unit button for more than 10 seconds; end by remote START/STOP.
- Do not operate test run longer than necessary.
12.3 Customer guidance
- Explain operation, mode selection, temperature setting, timers, airflow direction.
- Explain filter removal/cleaning and basic care requirements.
- 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.
- Forced cooling/test run method varies by controller type; follow the product procedure.
- Close the 2-way valve fully, then close the 3-way valve after a short run period, then stop operation.
14) Error codes (ASTH reference)
Errors may be indicated by indoor LED blink patterns (wireless) or displayed on wired remote controllers (optional). Capture the code and follow standard diagnostic workflow (power, wiring, comms, sensors, motors, PCB).
Document control: This Solution article is a consolidated, text-only field reference for KMTD series installation. Always comply with local regulations and refer to the latest manufacturer documentation for detailed procedures, diagrams, and regional variations.
14) Error codes (ASTH reference) – KMTD Series
If using a wired remote controller, error codes appear on the remote display. If using a wireless remote controller, refer to the indoor unit indicator lamp blinking patterns. Error display is shown only during operation (the table may include codes not relevant to this model series).
14.1 Indoor unit lamp indications (wireless)
- LED1: OPERATION indicator lamp (green)
- LED2: TIMER indicator lamp (orange)
- LED3: ECONOMY indicator lamp (green)
14.2 Error code list
| Error code | Description (summary) |
|---|
| 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 or refrigerant circuit address setting error (simultaneous multi-split type) |
| 22 | Indoor unit capacity error |
| 23 | Combination error |
| 24 | Connection unit number error (system dependent: indoor secondary / branch unit) |
| 26 | Indoor unit address setting error |
| 27 | Primary/secondary unit setup error (simultaneous multi-split type) |
| 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 |
| 54 | Electric air cleaner reverse VDD error |
| 55 | Filter set error |
| 57 | Damper error |
| 58 | Intake grille error |
| 59 | Indoor unit fan motor 2 error (Left side fan) |
| 5A | Indoor unit fan motor 3 error (Right side fan) |
| 5U | Indoor unit error |
| 61 | Outdoor unit reverse/missing phase and wiring error |
| 62 | Outdoor unit main PCB model information error or communication error |
| 63 | Inverter error |
| 64 | Active filter error / PFC circuit error |
| 65 | Trip terminal L error / IPM temperature error |
| 68 | Outdoor unit 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 unit heat exchanger liquid temperature sensor error |
| 74 | Outdoor temperature sensor error |
| 75 | Suction gas temperature sensor error |
| 76 | 2-way valve temperature sensor error / 3-way valve temperature sensor error |
| 77 | Heat sink temperature sensor error |
| 82 | Sub-cool heat exchanger gas inlet/outlet temperature sensor error |
| 83 | Liquid pipe temperature sensor error |
| 84 | Current sensor error |
| 86 | Discharge pressure sensor error / Suction pressure sensor error / 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 | Coil (expansion valve) 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 (flexible multi-split type) |
14.3 Wired remote controller (optional) – how to view error details
- If an error occurs, an error icon appears on the “Monitor mode screen”.
- Touch [Status] → then [Error Information].
- The displayed 2-digit number corresponds to the error code in the table.
- Use [Next page]/[Previous page] to switch between connected indoor units.
14.4 How to check / erase error memory
- To check error memory: stop the unit, disconnect power, reconnect power, then during the “3 minutes ST” period press and hold [MANUAL AUTO] on the indoor unit for 10 seconds or more.
- If there is no memorised error, “TEST RUN” is shown (operation and timer lamps blink simultaneously).
- To erase error memory: while “Error memory display” is shown, press [MANUAL AUTO] (a short beep sounds for ~3 seconds).
