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ARTG30/36/45LHTA - AOTG30/36/45LBTC Single Phase Slim Outdoor R410A Ducted Units

Freshdesk Solution Article - Technical Support Step-by-Step Phone Instructions
Safety position: This guide is for technical support coaching of licensed and competent service personnel only. Before live testing, confirm the person onsite is authorised, has PPE and suitable test equipment. For power-off tests, isolate supply and wait before touching electrical components. Do not instruct a customer or unqualified person to remove covers or perform electrical tests.

1. Document scope

AreaDetails
Indoor modelsARTG30LHTA, ARTG36LHTA, ARTG45LHTA
Outdoor slim modelsAOTG30LBTC, AOTG36LBTC, AOTG45LBTC
System typeR410A single phase inverter ducted system with slim outdoor unit.
Core electrical focusOutdoor power and communication checks include outdoor L-N supply, reverse transfer signal at terminal 1-3, and forward transfer signal at terminal 2-3.
PurposeProvide a Freshdesk-ready call guide with linked flowcharts, component tests, expected readings and ticket evidence requirements.

2. Error code quick reference

CodeManual fault descriptionPhone support action / linked test
E:11Serial communication errorE:11 communication split flow
E:12Wired remote controller communication error3 wire remote controller check
E:39Fan motor drive circuit error / indoor fan power supply errorIndoor fan motor / power PCB
E:41Indoor room thermistor errorThermistor testing
E:42Indoor heat exchanger thermistor errorThermistor testing
E:51Indoor unit fan motor 1 errorIndoor fan motor 1
E:53Drainage / drain pump errorDrain / float switch
E:59Indoor unit fan motor 2 errorIndoor fan motor 2
E:5UIndoor unit errorIntake and error confirmation
E:62Outdoor unit main PCB model information errorOutdoor PCB evidence
E:63Inverter errorInverter / filter PCB / transistor PCB flow
E:65IPM errorIPM error flow
E:71Discharge thermistor errorOutdoor thermistor testing
E:72Compressor thermistor errorOutdoor thermistor testing
E:73Heat exchanger middle/outlet thermistor errorOutdoor thermistor testing
E:74Outdoor thermistor errorOutdoor thermistor testing
E:77Heat sink thermistor errorMain PCB / heat sink thermistor
E:84Current sensor errorCurrent sensor / filter PCB
E:86Pressure sensor / high pressure switch errorPressure sensor / high pressure switch
E:94Over current errorOver current flow
E:95Compressor control errorCompressor control flow
E:97Outdoor unit fan motor errorOutdoor fan motor
E:994-way valve error4-way valve
E:A1Discharge temperature errorDischarge temperature flow
E:A3Compressor temperature errorCompressor temperature / refrigerant flow
E:A5Low pressure errorLow pressure flow

3. Quick map

Symptom / error familyMost likely areaJump to
No operation / remote blankSingle phase supply, indoor PCB remote supply, Y1/Y2/Y3 wiringRemote check
E:11Indoor/outdoor serial communication: reverse AC70-130 V at 1-3, forward AC70-130 V at 2-3Communication split flow
E:12 / remote commsY1/Y2/Y3 signal and indoor PCB CN14/CN140 remote supply3 wire remote flow
E:41/E:42/E:71/E:72/E:73/E:74/E:77Thermistor connector, resistance and PCB 5 V supplyThermistors
E:51/E:59/E:97Fan rotation, obstruction, motor short, PCB output voltageIndoor fan / Outdoor fan
E:63/E:65/E:94Inverter / IPM / overcurrent protectionE:63 / E:65 / E:94
E:95Compressor motor control / compressor harness / transistor PCBCompressor flow
E:A1/E:A33-way valve, EEV/strainer, fan/heat exchanger, thermistor, refrigerant chargeDischarge/compressor temp flow
E:A5Low pressure, valve position, fan/heat exchanger, EEV/strainer, pressure sensor, refrigerantLow pressure flow

4. GREAT-style linked flowcharts

E:11 communication split flow - Single phase slim outdoor

E:11 serial communication error or no indoor / outdoor communication
↓
↓
↓
Reverse transfer / outdoor signal path
Is AC70-130 V signal present at terminal 1-3?
YES
Outdoor signal is present. Check field cable, noise, earthing and indoor receiving side.
Forward transfer / indoor signal path
Is AC70-130 V signal present at terminal 2-3?
YES
Indoor signal is present. Check wiring integrity, noise/earth and outdoor receiving side.
NO
Indoor controller PCB becomes suspect only after wiring, supply and external-noise checks are proven.
Useful linked checks
Important split: For this slim outdoor single phase series, reverse and forward transfer are both expected to swing AC70-130 V. Reverse is terminal 1-3; forward is terminal 2-3. Do not approve boards until supply, wiring, external noise/earthing and component loading checks are documented.

3 wire remote controller communication check flow

Wired remote communication error / no operation / remote signal check
↓
↓
↓
Y1-Y3 is 12 VDC
no less than 11.4 VDC
Remote has controller power. Continue to Y2 signal checks.
Y1-Y3 is 0 VDC
Check CN14 on ARTG30/36LHTA or CN140 on ARTG45LHTA, terminal 1-3. Manual reference is DC13 V supply to remote control.
Y1-Y3 below 11.4 VDC
Check cable length, poor joints, wrong polarity, damaged controller cable or loaded indoor PCB supply.
↓
Remove Y2 from the remote, keep conductor safe, then test between remote terminal Y2 and Y3
↓
Remote Y2-Y3 fluctuates 7-11 / 7-12 VDC pulse
Remote is producing signal. Continue to field cable signal check.
No pulse at remote Y2-Y3
Remote controller likely defective after confirming 12 VDC supply is correct.
↓
Test between disconnected Y2 wire going to indoor unit and Y3 COM
↓
Field Y2-Y3 fluctuates 7-11 / 7-12 VDC pulse
Indoor PCB is returning signal. Reconnect Y2. If communication still fails, inspect terminals, cable shielding/noise and controller condition.
No pulse on field Y2 wire
Check open cable / short to COM / incorrect terminal. If wiring is sound, suspect indoor controller PCB.
Record in ticket: Y1-Y3 supply voltage, remote Y2-Y3 pulse result, disconnected field Y2-to-Y3 pulse result, cable condition and CN14/CN140 1-3 voltage.

E:63 inverter error flow - Outdoor unit

Transistor PCB error information received from transistor PCB
↓
Reset power and confirm if inverter error returns
↓
Check external causes: voltage drop, momentary open circuit, poor earth, noise or cables near power line
↓
Check wiring between power supply, filter PCB and inverter / transistor PCB
↓
Check connector state and open cable condition
↓
If wiring and external causes are proven, filter PCB and inverter/transistor PCB become suspect
↓
External cause found
Correct supply/noise/earthing issue and retest before replacing parts.
Connector/wiring issue
Correct connector or wiring and reset power.
Wiring OK, fault remains
Escalate filter PCB and inverter/transistor PCB with readings/photos attached.
Important: E:63 requires external cause and wiring checks before PCB replacement. Record supply quality, earthing and connector condition.

E:65 IPM error flow - Outdoor unit

IPM error / abnormal current to IPM in main PCB
↓
Check outdoor unit electrical component connections: removed connector, loose terminal, incorrect connection or open cable
↓
Check outdoor fan operation, heat exchanger obstruction and whether fan rotates by hand
↓
Check outdoor fan motor test before PCB approval
↓
Check compressor winding resistance and compressor terminal connection
↓
Check transistor PCB / IPM
↓
If checks do not improve symptom, main PCB becomes suspect
↓
Connector issue found
Correct removed connector, loose terminal or mis-wiring and reset power.
Airflow or fan fault
Correct airflow/coil/fan issue before PCB approval.
Compressor abnormal
Escalate as compressor fault after values are recorded.
IPM abnormal
Replace transistor PCB after IPM readings are recorded.
Important: E:65 should be treated as an IPM/inverter protection issue. Prove connections, fan/airflow, compressor and transistor PCB before authorising boards.

E:94 over current error flow - Outdoor unit

Over current after inverter compressor start processing completed, repeated protection stop
↓
Check outdoor fan operation, outdoor heat exchanger, air passages and ambient temperature
↓
Check whether discharged air is being sucked back into the outdoor unit
↓
Check transistor PCB / IPM
↓
If checks do not improve symptom, main PCB becomes suspect
↓
If main PCB does not improve symptom, compressor becomes suspect
↓
Airflow / heat exchanger issue
Clear obstruction, clean coil or correct recirculation before parts are replaced.
IPM abnormal
Replace transistor PCB after readings are recorded.
Main PCB suspected
Recommend main PCB only after airflow/fan/IPM evidence is documented.
Compressor suspected
Recommend compressor only after previous checks and main PCB sequence are completed.
Important: For E:94, the manual checks airflow/heat exchanger/ambient first, then IPM, then main PCB and compressor. Do not jump straight to compressor or PCB.

E:95 compressor control error flow - Outdoor unit

Compressor control error / rotor location out of phase protection
↓
Turn unit on and confirm whether abnormal compressor noise is present
↓
Isolate supply and visually inspect compressor harness cable, compressor terminals and transistor PCB connections
↓
Check compressor winding resistance U-V, V-W and U-W. Expected: 0.642 ohm at 20C for AOTG30LBTC; 0.432 ohm at 20C for AOTG36/45LBTC
↓
Check transistor PCB / IPM
↓
If transistor PCB and connections are normal but the error remains, main PCB then compressor sequence becomes suspect
↓
Abnormal compressor noise present
Record noise evidence and check compressor / harness before recommending compressor.
Harness burnt, loose, open or miswired
Repair or replace affected harness or terminal connection, then reset power and retest.
Compressor winding abnormal
Escalate as compressor fault after values are recorded.
IPM abnormal
Replace transistor PCB after readings are recorded.
Important: For E:95, physically inspect compressor harness and terminals. Do not replace inverter parts without recording compressor winding resistance and harness condition.

E:A1 discharge temperature / E:A3 compressor temperature flow - Outdoor unit

Discharge or compressor temperature protection during compressor operation
↓
Primary check: suspect refrigerant leak / insufficient refrigerant first
↓
Check 3-way valve is fully open: gas side in cooling, liquid side in heating as applicable
↓
Check EEV operation / coil resistance, capillary / strainer restriction and temperature difference across strainer
↓
Check outdoor fan operation and heat exchanger for foreign matter / blocked fins / recirculation
↓
Check discharge or compressor temperature thermistor value and DC 5 V PCB supply
↓
Leak or insufficient refrigerant found
Repair leak, pressure test, evacuate and weigh in charge as required.
3-way valve closed / not fully open
Open valve fully and re-test operation.
EEV / capillary / strainer issue
Confirm coil resistance, seating, operation noise and temperature difference across restriction.
Thermistor abnormal
Replace thermistor or repair harness only after value is confirmed against temperature.
All checks pass but fault remains
Main PCB/inverter control becomes suspect after refrigerant, valves, EEV, airflow and thermistor are proven.
Important: Treat E:A1/E:A3 as a refrigerant and system-condition fault first. The common causes are refrigerant leak, restriction, valves not fully open, fan/heat exchanger problems or thermistor error.

E:A5 low pressure error flow - Outdoor unit

Low pressure protection
↓
Check 3-way valve is fully open: gas side in cooling, liquid side in heating
↓
Check outdoor ambient and whether low pressure values are plausible
↓
Check outdoor fan operation, obstruction, recirculation and heat exchanger condition
↓
Check outdoor and indoor EEV operation and strainers for clogging
↓
Check solenoid valve SV1, pressure sensor characteristics and refrigerant amount
↓
Valve closed / restricted
Open valve fully, correct restriction and retest.
Ambient / airflow issue
Correct operating conditions, airflow, fan operation or blocked coil before replacing parts.
EEV / strainer issue
Check EEV coil, start-up noise, voltage and temperature difference across strainer.
Sensor / SV1 issue
Confirm pressure sensor voltage/operation and solenoid operation before PCB recommendation.
Refrigerant leak / undercharge
Repair leak, pressure test, evacuate and weigh in charge.
Important: Low pressure faults should be proven with valve position, airflow, EEV/strainer, SV1, sensor and refrigerant evidence before approving parts.

5. Step-by-step phone support SOPs

SOP 1 - Intake and safety gate

  1. Confirm caller name, company, site address, indoor model/serial and outdoor model/serial.
  2. Confirm exact complaint: error code, operating mode, when it occurs and whether it is repeatable.
  3. Confirm safety: no burning smell, water ingress, damaged wiring, repeated breaker trips or refrigerant odour.
  4. Confirm tools: multimeter with AC/DC volts, resistance and diode test.
  5. Decision point: if caller is not qualified or cannot identify terminals safely, stop at non-invasive checks and arrange authorised attendance.

SOP 2 - E:11 indoor/outdoor serial communication - slim single phase

  1. Reset power and confirm if E:11 returns.
  2. Check external causes such as poor earth, noise or equipment causing harmonic wave near power cable.
  3. Check interconnect and control unit connections for loose connector, open cable or mis-wiring.
  4. Check outdoor supply: expected AC216-264 V at outdoor terminal L-N.
  5. Reverse transfer signal: check outdoor terminal 1-3. Expected swing AC70-130 V.
  6. Forward transfer signal: check outdoor terminal 2-3. Expected swing AC70-130 V.
  7. If reverse transfer signal is abnormal, check outdoor fan motor, active filter module, transistor PCB/IPM and filter PCB CN110 before outdoor main PCB approval.
  8. If forward transfer signal is abnormal, suspect indoor controller PCB after wiring and supply are proven.

SOP 3 - 3 wire remote signal test

  1. At the rear of the wall controller, confirm Y1 = 12 V/red, Y2 = signal/white, Y3 = COM/black.
  2. Measure Y1 to Y3: expected 12 VDC, no less than 11.4 VDC.
  3. Manual PCB supply reference: CN14 terminal 1-3 for ARTG30/36LHTA or CN140 terminal 1-3 for ARTG45LHTA should be approximately DC13 V.
  4. Remove Y2 from the remote. Measure between remote terminal Y2 and Y3: expected fluctuating 7-11 / 7-12 VDC pulse.
  5. Measure between the disconnected Y2 wire going to the indoor unit and Y3: expected fluctuating 7-11 / 7-12 VDC pulse.
  6. If no 12 V supply, check indoor PCB remote power supply. If remote has supply but no Y2 pulse, suspect remote controller. If field Y2 has no return pulse, check cable and indoor controller PCB.

SOP 4 - Thermistor testing

  1. Isolate power. Check connector is not loose, removed, miswired or open.
  2. Disconnect thermistor and measure resistance out of circuit. Compare to actual bulb temperature.
  3. Indoor room thermistor rough values: 0C 33.6 kΩ, 5C 25.9 kΩ, 10C 20.2 kΩ, 15C 15.8 kΩ, 20C 12.5 kΩ, 25C 10.0 kΩ, 30C 8.0 kΩ, 35C 6.5 kΩ, 40C 5.3 kΩ, 45C 4.35 kΩ, 50C 3.59 kΩ.
  4. Indoor heat exchanger thermistor rough values: 0C 176 kΩ, 5C 134 kΩ, 10C 103 kΩ, 15C 80.3 kΩ, 20C 62.9 kΩ, 25C 49.7 kΩ, 30C 39.6 kΩ, 35C 31.7 kΩ, 40C 25.6 kΩ, 45C 20.8 kΩ, 50C 17.1 kΩ.
  5. Outdoor thermistor PCB 5 V checks: AOTG30LBTC discharge CN63 1-3, compressor CN64 1-3, pipe CN65 1-3, outdoor CN62 1-3. AOTG36/45LBTC discharge CN62 1-2, compressor CN62 3-4, pipe CN63 1-2 or 4-5, outdoor CN61 1-3.
  6. Replace thermistor only when resistance is open/short/out of table. Replace PCB only when connector/wiring and thermistor are proven.

SOP 5 - Indoor fan motor testing

  1. Power off. Rotate fan by hand and check for obstruction, bearing lock, dropped fan or casing contact.
  2. Check ambient temperature around the motor and confirm no external heat source is affecting it.
  3. Check indoor fan motor using Service Parts Information: circuit-test winding coil resistance U, V, W and location sensor circuit test.
  4. For E:39, check external cause, connector condition and indoor power supply PCB before board replacement.
  5. Record fan rotation, motor reading, connector condition and PCB decision.

SOP 6 - Outdoor fan motor testing

  1. Power off. Rotate fan by hand and check obstruction, bearing lock, fan guard contact or damaged fan.
  2. Check ambient temperature around the motor and confirm no external heat source is affecting it.
  3. Check outdoor fan motor using circuit-test between Vm and GND. If short-circuited below 300 kΩ, replace outdoor fan motor and main PCB.
  4. Pin references: Red = Vm DC voltage; Black = GND; White = Vcc control voltage; Yellow = Vsp speed command; Brown = PG feedback. Some harness order differs between models, so identify by wire colour and symbol.
  5. On E:11 reverse transfer faults, abnormal outdoor fan motor can load the signal path. Check fan motor before outdoor PCB approval.

SOP 7 - EEV and strainer testing

  1. Check EEV connector for loose connector or open cable.
  2. Remove connector and check EEV coil resistance. For this family, use the relevant EEV coil pair list from the circuit diagram; common expected coil value is 46 Ω ±4 Ω at 20C.
  3. Remove connector and check PCB drive voltage: expected DC12 V.
  4. Turn on power and listen/feel for EEV start-up operation noise.
  5. Check opening/closing effect by temperature difference. Closed valve creates inlet/outlet temperature difference; open valve has no temperature difference.
  6. Check strainer. A temperature difference across the strainer suggests internal clogging.

SOP 8 - Compressor testing

  1. Check compressor terminal connection and transistor PCB connection for loose or incorrect wiring.
  2. Check winding resistance between U-V, V-W and U-W. Manual value: AOTG30LBTC = 0.642 Ω at 20C; AOTG36/45LBTC = 0.432 Ω at 20C.
  3. If resistance is 0 or infinite, replace compressor.
  4. If compressor does not start or stops soon, also check gas pipe valve open, refrigerant leak, strainer clogging and harness condition before compressor approval.
  5. If Check Point 1 and 2 do not improve the symptom and compressor is normal, main PCB / transistor PCB sequence becomes suspect.

SOP 9 - Active filter module

  1. Use this for E:11 reverse transfer abnormal signal follow-on, no-power style inverter-link faults and active filter checks from the service parts section.
  2. Check external causes first: voltage drop, momentary power failure, defective contact, noise and grounding.
  3. Check active filter module for open/short-circuit and diode condition.
  4. Check output DC voltage between P and N while compressor is stopped and operating.
  5. If output voltage during compressor operation is less than stopped output voltage, replace active filter module.

SOP 10 - Transistor PCB / IPM

  1. Use this for E:63 inverter error, E:65 IPM error, E:94 overcurrent and E:95 compressor control error.
  2. Confirm L-N supply is within range before board approval.
  3. Inspect transistor PCB connections and harnesses for loose connectors, corrosion, open cable or burn marks.
  4. Check compressor winding and outdoor fan motor loading before recommending transistor PCB.
  5. Attach photos and readings to ticket before board approval.

SOP 11 - Pressure sensor / high pressure / low pressure

  1. Check pressure sensor or high pressure switch connector and wiring condition.
  2. High pressure switch reference: contact changes at approximately 4.2 ±0.1 MPa and returns at approximately 3.2 ±0.15 MPa.
  3. For A5, check valve position, ambient, outdoor fan, EEV/strainer, SV1 and refrigerant amount before sensor or PCB replacement.
  4. Record actual pressure, operating mode, pipe temperatures, sensor reading and refrigerant evidence.

SOP 12 - Drain / float switch

  1. Check float switch operation and any blockage by dust.
  2. Remove float switch and check ON/OFF switching operation by meter.
  3. Check CN09 on ARTG30/36LHTA or CN120 on ARTG45LHTA, plus shorted / pinched wire.
  4. Check drain hose for clogging, traps or poor fall.
  5. If all checks are normal and drainage error remains, controller PCB becomes suspect.

SOP 13 - 4-way valve

  1. Check connector is fitted, not miswired and no open cable.
  2. Check relevant thermistors are fitted in holders and not pinched or reading incorrectly.
  3. Check solenoid coil / valve operation where accessible.
  4. Check valve position by piping temperature difference. If valve position is not correct after coil and thermistors are proven, valve may be faulty.
  5. If checks pass and error remains, board control becomes suspect.

SOP 14 - Current sensor

  1. Reset power and confirm if current sensor error returns.
  2. Check external causes: voltage drop, momentary open circuit, noise and grounding.
  3. Check outdoor electrical component connectors, terminal tightness, miswiring and open cables.
  4. Manual sequence is filter PCB first if the checks do not improve the symptom, then main PCB if filter PCB does not resolve it.

6. Ticket evidence checklist

Evidence requiredDetails to record
Model and serialIndoor and outdoor model/serial, controller type and exact error display.
Safety and site conditionWho is onsite, licence/competency confirmation, power isolation status, access limitations, water ingress/burning smell/short circuit risk.
Electrical readingsL-N supply voltage, reverse/forward communication readings, remote Y1/Y2/Y3 readings, fan motor Vm/GND result, PCB 5 V / 12 V / 13 V checks.
Component readingsThermistor kΩ and measured temperature, EEV coil Ω, compressor winding Ω, transistor PCB/IPM observations, active filter result.
Refrigeration evidenceValve positions, operating mode, ambient, fan operation, coil condition, pressures, leak test, strainer temperature difference, weighed charge details.
Approval decisionState what has been proven before recommending motor, thermistor, compressor, active filter, transistor PCB/IPM, main PCB, controller PCB or power PCB.