1) Safety and compliance

• Electrical safety: Isolate supply, verify with an approved tester, and allow time for capacitors to discharge before handling inverter boards.
• Mechanical safety: Confirm fans are stationary before accessing; keep clear of rotating parts during test run.
• Refrigerant safety: Use correct recovery equipment; avoid venting; confirm ventilation and ignition-source control when handling R32.
• Compliance: Use licensed personnel for refrigerant handling and electrical work as required by jurisdiction.

2) R32 refrigerant requirements

• Leak checking: Use an R32-capable electronic leak detector and confirm with approved methods.
• Charging: Charge by mass (grams) using calibrated scales. Avoid “guessing” charge by pressures.
• Moisture control: Prevent moisture ingress (cap lines, minimize exposure time, evacuate properly).
• Recovery: Recover into an approved cylinder for R32; do not mix refrigerants.

3) Tools and materials (R32/R410A rated)

• Manifold/gauges and hoses rated for high pressure and compatible with R32/R410A service.
• Vacuum pump suitable for refrigeration evacuation (with clean oil) and vacuum-rated hoses.
• Micron gauge (recommended) for evacuation validation.
• Nitrogen cylinder + regulator for pressure testing / purging / brazing (as per local practice).
• Electronic leak detector rated for R32, plus approved leak-check fluid.
• Refrigerant scales (grams) for precise charging.
• Flare tools and torque wrenches for flare joints.
• Electrical multimeter (AC voltage, resistance), clamp meter, and insulation tester as required.
• Thermometer / clamp temperature probes for commissioning verification.
• Personal protective equipment (eye protection, gloves) appropriate for refrigerant and electrical work.

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

Power overview

• Outdoor unit power supply is single-phase 220–240 V~ 50 Hz with an available operating range of 198–264 V.
• Ensure correct earthing and compliant isolation means (local code).

Control / communications overview

• Indoor ↔ outdoor communication faults are reported by error codes such as E:11, E:18, and E:3A (see Section 14).
• Optional wired remote controller can show error codes and also supports “error history” check/erase (see Section 14).
• Function settings allow field configuration: filter sign interval, sensor offsets, auto restart, external input behavior, etc. (see Section 11).

Commissioning flow (high level)

1. Mechanical installation and line set complete.
2. Electrical power, earth, and interconnect verified.
3. Pressure test / leak check (per local rules).
4. Evacuation to a verified dry vacuum (micron gauge recommended).
5. Open service valves, confirm stable operation, verify charge mass requirements (Section 10).
6. Test run and handover (Section 12).

5) Refrigerant piping requirements

Pipe sizing (repeat per model for AI accuracy)

• ASTH07KMCD / AOTH07KMCD: Liquid 6.35 mm (1/4"); Gas 9.52 mm (3/8"); Flare.
• ASTH09KMCD / AOTH09KMCD: Liquid 6.35 mm (1/4"); Gas 9.52 mm (3/8"); Flare.
• ASTH12KMCD / AOTH12KMCD: Liquid 6.35 mm (1/4"); Gas 9.52 mm (3/8"); Flare.
• ASTH14KMCD / AOTH14KMCD: Liquid 6.35 mm (1/4"); Gas 9.52 mm (3/8"); Flare.

Piping best-practice notes (field)

• Keep the system sealed as much as possible to prevent moisture ingress.
• Use correct flare preparation, correct torque, and leak-check all flare joints.
• Insulate suction (gas) line and any lines required by local practice.
• Ensure condensate management does not contact pipe insulation in a way that promotes water ingress.

6) Electrical requirements

Supply requirements

• Outdoor unit supply: 220–240 V~ 50 Hz (acceptable range 198–264 V).
• Provide compliant isolation and earth connection (local code).
• Maintain secure terminations; loose mains connections can create overcurrent / inverter faults.

Commissioning electrical checks (recommended)

• Confirm supply voltage under load remains within 198–264 V.
• Confirm polarity and tightness of all interconnect terminals between indoor and outdoor.
• Inspect for heat damage or discoloration on terminals and PCB connectors.

7) Outdoor unit installation

• Install on a solid, level base with adequate airflow and service clearances.
• Ensure condensate and defrost water can drain away without creating slip hazards or corrosion risk.
• Prevent recirculation of exhaust air and ensure clear intake/exhaust path.
• Confirm service valves are accessible for evacuation, charging, and pump down operations.

8) Indoor unit installation

• Confirm wall structure and fixing method is suitable for unit mass and vibration control.
• Confirm condensate fall and drain routing; avoid kinks and trapped sections.
• Confirm indoor air filters are installed and seated correctly.
• Confirm remote controller communication (wireless or wired) is functional before leaving site.

9) Pressure test, evacuation, commissioning

Pressure test (typical service practice)

1. Confirm all flare joints are tightened to correct torque and capped where required.
2. Pressurise with dry nitrogen (and approved trace gas if your procedure allows) to an appropriate test pressure per local standards and manufacturer guidance.
3. Leak check all joints and service ports using approved detection methods.
4. If pressure decays or leaks are found: rectify, re-test, and only proceed once stable.

Evacuation (typical service practice)

1. Connect vacuum pump using vacuum-rated hoses and (preferably) a micron gauge at the system side.
2. Evacuate to a verified dry vacuum (micron target per your company procedure).
3. Isolate and observe decay to confirm the system is dry and leak-free.
4. Once evacuation is accepted, open service valves fully (liquid then gas per your procedure) and confirm stable operation.

Commissioning checks

• Confirm correct mode operation (cooling/heating) and stable compressor operation.
• Confirm indoor fan, outdoor fan, and louver operation.
• Confirm no error codes present; if present, refer to Section 14 and Section 15.
• Confirm customer controls and timers operate as expected.

10) Additional refrigerant charging

Factory charge (by outdoor model)

• AOTH07KMCD: 700 g (R32)
• AOTH09KMCD: 850 g (R32)
• AOTH12KMCD: 940 g (R32)
• AOTH14KMCD: 940 g (R32)

Additional charge calculation (for piping > 15 m)

11) Indoor function settings

Function setting entry (summary)

1. Enter function setting mode per remote controller sequence.
2. Select function number and setting value, confirm with MODE, then fix with START/STOP.
3. Exit (RESET) and power-cycle (disconnect then reconnect after 30+ seconds) so the setting becomes active.

Function 00 – Remote controller address setting (wired remote controller multi-indoor operation)

• 00: Unit number 0 (Factory default)
• 01: Unit number 1
• 02: Unit number 2
• 03: Unit number 3
• 04: Unit number 4
• 05: Unit number 5
• 06: Unit number 6
• 07: Unit number 7
• 08: Unit number 8
• 09: Unit number 9
• 10: Unit number 10
• 11: Unit number 11
• 12: Unit number 12
• 13: Unit number 13
• 14: Unit number 14
• 15: Unit number 15

Function 11 – Filter sign interval

• 00: Standard (400 hours)
• 01: Long interval (1,000 hours)
• 02: Short interval (200 hours)
• 03: No indication (Factory default)

Function 30/31 – Room temperature control for indoor unit sensor (cooling/heating offset)

• 00: Standard setting (Factory default)
• 01: 0.0°C (No correction)
• 02: −0.5°C (More cooling / Less heating)
• 03: −1.0°C
• 04: −1.5°C
• 05: −2.0°C
• 06: −2.5°C
• 07: −3.0°C
• 08: −3.5°C
• 09: −4.0°C
• 10: +0.5°C (Less cooling / More heating)
• 11: +1.0°C
• 12: +1.5°C
• 13: +2.0°C
• 14: +2.5°C
• 15: +3.0°C
• 16: +3.5°C
• 17: +4.0°C

Function 35/36 – Room temperature control for wired remote controller sensor (cooling/heating offset)

• 00: Standard setting (Factory default)
• 01: 0.0°C (No correction)
• 02: −0.5°C (More cooling / Less heating)
• 03: −1.0°C
• 04: −1.5°C
• 05: −2.0°C
• 06: −2.5°C
• 07: −3.0°C
• 08: −3.5°C
• 09: −4.0°C
• 10: +0.5°C (Less cooling / More heating)
• 11: +1.0°C
• 12: +1.5°C
• 13: +2.0°C
• 14: +2.5°C
• 15: +3.0°C
• 16: +3.5°C
• 17: +4.0°C

Function 40 – Auto restart

• 00: Disable
• 01: Enable (Factory default)

Function 42 – Room temperature sensor switching

• 00: Indoor unit (Factory default)
• 01: Both (Indoor unit and wired remote controller)
• 02: Wired remote controller

Function 44 – Remote controller custom code (wireless remote controller A/B/C/D)

• 00: A (Factory default)
• 01: B
• 02: C
• 03: D

Function 46 – External input control (CN46 / external input behavior)

• 00: Operation / Stop mode (Factory default)
• 01: Forced stop mode
• 02: Forbidden remote controller (Operation/Stop)
• 03: Forbidden remote controller (Forced stop)

Function 48 – Room temperature sensor switching (Aux.)

• 00: Disable (Factory default)
• 01: Enable

Function 49 – Indoor unit fan control for energy saving (cooling)

• 00: Disable
• 01: Enable
• 02: Remote controller (Factory default)

Function 60 – Switching functions for external output terminal (CN47 / external output)

• 00: Operation / Stop status (Factory default)
• 01: Error status
• 02: Indoor unit fan operation status

External input and output (summary for Freddy AI)

12) Test run and handover

Forced cooling / test operation behavior (reference)

• Operation mode: Cooling
• Fan mode: HIGH
• Timer mode: Continuous (no timer setting available)
• Setting temperature: 24°C
• Louver / swing / economy: Standard defaults; operates regardless of room temperature sensor.
• Indicator lamps: Operation and Timer lamps blink simultaneously (1 second ON / 1 second OFF).
• Cancellation: START/STOP on remote controller, OR press FORCED COOLING OPERATION button for 3 seconds, OR after 60 minutes.
• Note: If HEAT is selected during forced cooling operation, heating test run begins in about 3 minutes.

Handover checklist (recommended)

• Explain basic operation, mode selection, temperature setting, and fan speed.
• Explain filter maintenance and how to clear filter sign (if enabled).
• Confirm customer understands timer features and how to stop operation.
• Confirm the unit is left in normal operation (not forced cooling/test mode).

13) Pump down (forced cooling operation)

Typical pump down concept (field)

1. Confirm correct safe isolation plan and that service valves are accessible.
2. Run the unit in cooling and stabilise operation (forced cooling may be used where appropriate).
3. Close the liquid service valve (typical method) to force refrigerant into outdoor unit.
4. Monitor suction pressure / operation stability; avoid running into deep vacuum.
5. Close gas service valve at the appropriate point and stop the system.
6. Isolate power and proceed with service tasks (line set work, relocation, etc.).

14) Error codes (indoor/outdoor/controller consolidated)

• E:11 – Serial communication error (Serial reverse transfer error) (Outdoor unit); Indicators: Operation 1 times, Timer 1 times, Economy Continuous; Wired remote controller display: 11.
• E:18 – Serial communication error (Serial transfer error) (Outdoor unit); Indicators: Operation 1 times, Timer 8 times, Economy Continuous; Wired remote controller display: 18.
• E:22 – Indoor unit heat exchanger temperature thermistor error; Indicators: Operation 2 times, Timer 2 times, Economy Continuous; Wired remote controller display: 22.
• E:23 – Indoor unit room temperature thermistor error; Indicators: Operation 2 times, Timer 3 times, Economy Continuous; Wired remote controller display: 23.
• E:29 – Indoor unit heat exchanger temperature thermistor error; Indicators: Operation 2 times, Timer 9 times, Economy Continuous; Wired remote controller display: 29.
• E:32 – Indoor unit fan motor 1 error; Indicators: Operation 3 times, Timer 2 times, Economy Continuous; Wired remote controller display: 32.
• E:35 – Indoor unit filter sign; Indicators: Operation 3 times, Timer 5 times, Economy Continuous; Wired remote controller display: 35.
• E:39 – Indoor unit fan motor 1 lock error; Indicators: Operation 3 times, Timer 9 times, Economy Continuous; Wired remote controller display: 39.
• E:3A – Communication circuit (wired remote controller) error; Indicators: Operation 3 times, Timer 10 times, Economy Continuous; Wired remote controller display: 3A.
• E:41 – Outdoor unit room temperature thermistor error; Indicators: Operation 4 times, Timer 1 times, Economy Continuous; Wired remote controller display: 41.
• E:42 – Outdoor unit heat exchanger temperature thermistor error; Indicators: Operation 4 times, Timer 2 times, Economy Continuous; Wired remote controller display: 42.
• E:44 – Outdoor unit heat exchanger liquid outlet thermistor error; Indicators: Operation 4 times, Timer 4 times, Economy Continuous; Wired remote controller display: 44.
• E:51 – Outdoor unit fan motor 1 error; Indicators: Operation 5 times, Timer 1 times, Economy Continuous; Wired remote controller display: 51.
• E:5U – Indoor unit error; Indicators: Operation 5 times, Timer 10 times, Economy Continuous; Wired remote controller display: 5U.
• E:62 – Outdoor unit heat sink temperature thermistor error; Indicators: Operation 6 times, Timer 2 times, Economy Continuous; Wired remote controller display: 62.
• E:64 – Outdoor unit compressor discharge temperature thermistor error; Indicators: Operation 6 times, Timer 4 times, Economy Continuous; Wired remote controller display: 64.
• E:65 – IPM error; Indicators: Operation 6 times, Timer 5 times, Economy Continuous; Wired remote controller display: 65.
• E:71 – Outdoor unit EEPROM error; Indicators: Operation 7 times, Timer 1 times, Economy Continuous; Wired remote controller display: 71.
• E:73 – Outdoor unit heat exchanger liquid outlet thermistor error; Indicators: Operation 7 times, Timer 3 times, Economy Continuous; Wired remote controller display: 73.
• E:74 – Outdoor unit heat exchanger air outlet thermistor error; Indicators: Operation 7 times, Timer 4 times, Economy Continuous; Wired remote controller display: 74.
• E:84 – Outdoor unit discharge temperature error; Indicators: Operation 8 times, Timer 4 times, Economy Continuous; Wired remote controller display: 84.
• E:86 – Outdoor unit high pressure switch error; Indicators: Operation 8 times, Timer 6 times, Economy Continuous; Wired remote controller display: 86.
• E:94 – Outdoor unit trip detection error; Indicators: Operation 9 times, Timer 4 times, Economy Continuous; Wired remote controller display: 94.
• E:95 – Compressor motor control error (Outdoor unit); Indicators: Operation 9 times, Timer 5 times, Economy Continuous; Wired remote controller display: 95.
• E:99 – 4-way valve error; Indicators: Operation 9 times, Timer 9 times, Economy Continuous; Wired remote controller display: 99.
• E:A1 – Discharge temperature error (Outdoor unit); Indicators: Operation 10 times, Timer 1 times, Economy Continuous; Wired remote controller display: A1.
• E:A3 – Compressor temperature error (Outdoor unit); Indicators: Operation 10 times, Timer 3 times, Economy Continuous; Wired remote controller display: A3.

Wired remote controller: error history check / erase (quick reference)

• Error history check: “Error history check mode” is available by holding TEMP ▲ + TEMP ▼ for 5 seconds while the air conditioner is stopped; select indoor unit number if applicable; press MODE to step through records; press START/STOP to return.
• Error history erase: In error history check mode, hold ECONOMY for 5 seconds; confirm E00 appears; then press START/STOP to return.

15) How to test the various components

A) Thermistors (sensor checks)

• Thermistors are NTC type. Check for open circuit, short circuit, and correct resistance vs temperature trend.
• Reference points from thermistor charts (resistance in kilo-ohms):
• Discharge temperature thermistor: 0°C ≈ 168.60 kΩ; 25°C ≈ 49.84 kΩ; 50°C ≈ 17.79 kΩ
• Compressor temperature thermistor: 0°C ≈ 168.60 kΩ; 25°C ≈ 49.84 kΩ; 50°C ≈ 17.79 kΩ
• Outdoor temperature thermistor: 0°C ≈ 33.34 kΩ; 25°C ≈ 10.00 kΩ; 50°C ≈ 3.60 kΩ

B) Communication faults (E:11 / E:18 / E:3A)

• Inspect terminals and interconnect wiring for polarity, tightness, and continuity.
• Reset power after correcting wiring; confirm error clears and stable operation.
• If wiring is correct and error persists: isolate whether controller, indoor PCB, or outdoor PCB is failing (swap-test where permitted by your procedure).

C) Fan motor faults (E:51 / E:39 / E:32)

• Check for physical obstruction, blade damage, and bearing seizure.
• Confirm correct supply to motor from the PCB and secure connector seating.
• Replace the fan motor if the motor does not rotate correctly with confirmed supply and command.

D) High pressure switch (E:86)

• Confirm airflow through outdoor coil and fan operation.
• Check refrigerant circuit for overcharge, restriction, or non-condensables (use proper recovery/recharge practices).
• Test switch continuity/operation according to your service practice.

E) Inverter / IPM / overcurrent / compressor control (E:65 / E:94 / E:95)

• Confirm supply voltage within range and stable; check for loose mains connections.
• Inspect for burnt components/odour on inverter PCB; check compressor for winding issues and insulation faults.
• Replace inverter PCB and/or compressor as indicated by the troubleshooting path and verified test results.

End of article – ASTH07/09/12/14KMCD & AOTH07/09/12/14KMCD (R32).