ARTG30/36/45LHTA - AOTG30/36/45LBTC R410A Ducted Units
Freshdesk Solution Article - Phone Support Procedure with Model-Specific Electrical Readings
Safety position: This article is for coaching licensed and competent service personnel only. Do not ask a customer or unqualified person to remove covers or complete live electrical tests. For power-off checks, isolate supply, verify isolation and wait for capacitors to discharge before touching electrical components. DC bus, IPM, ACTPM and fan motor circuits can retain hazardous voltage.
ScopeCritical readingsTriage flowError displayCommunicationRemote signalThermistorsIndoor fanOutdoor fanEEV readingsPressure sensorCompressorIPM / ACTPMDiode bridge4-way valveDrain / floatDefrostTest run / pump downTicket checklist
1. Scope and source alignment
| Area | Details |
|---|---|
| Models covered | Indoor: ARTG30LHTA, ARTG36LHTA, ARTG45LHTA Outdoor: AOTG30LBTC, AOTG36LBTC, AOTG45LBTC |
| Platform | R410A inverter ducted, 240 V 50 Hz single phase outdoor platform. Use the exact indoor/outdoor model combination before applying readings. |
| Primary manual use | Service Instruction Manual AOTG30/36/45LBTC for operational logic, error code troubleshooting, EEV control, pump down, defrost and service parts information. |
| Primary service manual use | Service Manual ARTG__LHTA - AOTG__LBTC for specifications, refrigerant diagrams, circuit diagrams, connector locations, PCB diagrams and model-specific component readings. |
| Training overlay | Service Agent Training used for how to coach the tests: DC fan motor test method, diode bridge, ACTPM, thermistors, pressure transducer, EEV, compressor and safe evidence capture. |
How this version is different
This version includes the readings that should be captured on the ticket: compressor winding resistance, thermistor kΩ/voltage values, EEV coil resistance, DC fan terminal checks, ACTPM resistance checks, diode bridge values, 4-way valve coil value and pressure sensor checks.
2. Critical readings - use this first during the phone call
Important
Where there is a model-specific reading below, use it instead of a generic training value. Readings are temperature dependent. Confirm actual sensor bulb temperature before judging thermistors.
| Component | AOTG30LBTC | AOTG36LBTC / AOTG45LBTC | Action if outside range |
|---|---|---|---|
| Compressor winding resistance | U-V / V-W / U-W: 0.642 Ω at 20°C | U-V / V-W / U-W: 0.432 Ω at 20°C | All three windings should be balanced. If open, shorted, unequal or insulation to earth is poor, do not condemn PCB until compressor is proven. |
| Compressor insulation | Use insulation tester from each compressor terminal to earth. Training benchmark: greater than 1 MΩ. | Use insulation tester from each compressor terminal to earth. Training benchmark: greater than 1 MΩ. | If below benchmark, treat as compressor insulation failure / contamination risk. |
| EEV coil | Connector CN700. Red common to Blue / Orange / Yellow / White: 46.0 Ω at 20°C. | Connector CN111. Red common to Blue / Orange / Yellow / White: 46.0 Ω at 20°C. | Open, short or uneven coil readings support EEV coil replacement. If coil is correct, check PCB DC drive, valve movement noise and strainer/refrigerant symptoms. |
| EEV PCB drive | During power-up, confirm EEV initialization/noise and DC drive command. | During power-up, confirm EEV initialization/noise and DC drive command. | If coil is correct but no drive/no initialization, suspect main PCB after confirming connector and wiring. |
| 4-way valve coil | AC 240 V ON in heating. Coil DC resistance: 1355 Ω ±10% at 20°C. | AC 240 V ON in heating. Coil DC resistance: 1355 Ω ±10% at 20°C. | If voltage present but valve does not shift, check coil and valve body. If no voltage, check PCB/control. |
| Outdoor DC fan motor | Connector CN800. Vm to GND should not be shorted; if below 300 kΩ, replace fan motor and main PCB. | Connector CN800. Vm to GND should not be shorted; if below 300 kΩ, replace fan motor and main PCB. | Do not disconnect fan while powered. Confirm rotation, connector, Vm/GND short, control voltage and feedback. |
| Indoor DC fan motor | Connector CN105 on ARTG30/36. Vm to GND short check; fan supply values include DC340 V, DC15 V, DC13.5 V, DC12 V, DC5 V circuits. | ARTG45 uses the larger indoor platform and dual fan arrangement; check fan motor 1/2 fault path and connector before PCB. | If fan/bearing locked or Vm-GND short is found, replace fan motor and relevant PCB as per service parts logic. |
| DC bus | Training benchmark at DC IN plug: 330-380 V DC on single phase inverter platform. | Training benchmark at DC IN plug: 330-380 V DC on single phase inverter platform. | If AC is present but no DC bus, check relay, diode bridge, ACTPM, filter/capacitor PCB and shorted loads. |
| Choke coil | 0.32 mH 30 A; DC resistance 45 mΩ max at 20°C. | 0.32 mH 30 A; DC resistance 50 mΩ max at 20°C. | Open/high resistance can affect power conversion. |
| PTC thermistor | Initial resistance 40 Ω ±25% at 25°C. | Initial resistance 40 Ω ±25% at 25°C. | Check for open, crack or burn marks. |
3. Clickable triage flow
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4. Error display and quick direction
| Error group | Meaning / direction | Go to |
|---|---|---|
| 1-1 | Serial communication error | Communication |
| 1-2 | Wired remote controller communication error | Remote signal |
| 4-1 / 4-2 | Indoor room or heat exchanger thermistor error | Thermistors |
| 5-1 / 5-9 | Indoor fan motor error | Indoor fan |
| 5-3 | Drainage error | Drain / float |
| 6-3 / 6-4 / 6-5 | Inverter, active filter/PFC, IPM error | IPM / ACTPM and diode bridge |
| 7-1 / 7-2 / 7-3 / 7-4 | Outdoor thermistor group | Thermistors |
| 9-5 / pressure related | Pressure switch/sensor or pressure protection | Pressure sensor |
| 9-7 / outdoor fan | Outdoor fan motor | Outdoor fan |
| A / compressor location / start related | Compressor, IPM or wiring | Compressor and IPM |
5. Communication and power checks
| Step | Ask / test | Expected / decision |
|---|---|---|
| 1 | Confirm terminal wiring between indoor and outdoor: active/neutral/signal/earth as per wiring diagram. | Do not proceed until wiring, polarity and loose terminals are corrected. |
| 2 | Confirm AC supply at outdoor and indoor terminals. | Use model nameplate current and power source; isolate before touching terminals. |
| 3 | If AC present but outdoor has no DC bus, go to inverter power checks. | Expected DC bus on this platform is typically 330-380 V DC at DC IN. |
| 4 | Check whether the EEV energises/initialises at power-up. | No EEV movement can indicate no PCB drive, no DC supply, open EEV coil or main PCB issue. |
| 5 | Check error history and LED/display state before resetting. | Ticket must include original code, LED pattern and whether fault returns after reset. |
6. Wired remote signal checks
| Test point | Expected reading | Decision |
|---|---|---|
| Y1 to Y3 at controller | 12 V DC, no less than 11.4 V DC | If missing, check controller board / power supply path. |
| Remove Y2; test Y3 to cable going to indoor | Fluctuating 7-11 V DC pulse | If missing, suspect signal line, controller or indoor PCB path. |
| Y2 to Y3 at controller terminals | Fluctuating 7-11 V DC pulse | If missing, check remote controller, wiring and terminal connection. |
7. Thermistor readings
Test method
- Power off and unplug the thermistor from PCB for resistance checks.
- Measure bulb temperature separately and compare to the closest row.
- For live PCB checks, confirm 5 V DC sensor circuit only where safe and qualified.
- Open circuit, short circuit or reading inconsistent with actual temperature supports thermistor/wiring replacement before PCB.
Outdoor thermistors - AOTG30LBTC
| Thermistor | Connector / circuit | 0°C | 20°C | 30°C |
|---|---|---|---|---|
| Discharge temp. | CN62-CN65 group | 175.7 kΩ / 0.3 V | 64.5 kΩ / 0.8 V | 41.1 kΩ / 1.2 V |
| Compressor temp. | CN62-CN65 group | 168.6 kΩ / 0.4 V | 62.6 kΩ / 0.9 V | 40.0 kΩ / 1.2 V |
| Pipe temp. | CN62-CN65 group | 16.1 kΩ / 1.1 V | 6.1 kΩ / 2.2 V | 4.0 kΩ / 2.7 V |
| Outdoor temp. | CN62-CN65 group | 35.2 kΩ / 2.6 V | 12.6 kΩ / 3.8 V | 8.0 kΩ / 4.1 V |
Outdoor thermistors - AOTG36LBTC / AOTG45LBTC
| Thermistor | Connector / circuit | 0°C | 20°C | 30°C |
|---|---|---|---|---|
| Discharge temp. | CN62 | 168.6 kΩ / 0.4 V | 62.6 kΩ / 0.9 V | 40.0 kΩ / 1.2 V |
| Compressor temp. | CN63 | 168.6 kΩ / 0.4 V | 62.6 kΩ / 0.9 V | 40.0 kΩ / 1.2 V |
| Pipe mid / pipe temp. | CN61-CN63 group | 16.1 kΩ / 1.1 V | 6.0 kΩ / 2.2 V | 3.8 kΩ / 2.8 V |
| Outdoor temp. | CN61 | 35.2 kΩ / 2.6 V | 12.6 kΩ / 3.8 V | 8.0 kΩ / 4.1 V |
Indoor thermistors - ARTG30LHTA / ARTG36LHTA
| Thermistor | Connector | 0°C | 20°C | 30°C |
|---|---|---|---|---|
| Pipe temp. | CN5 | 176.0 kΩ / 1.1 V | 62.9 kΩ / 2.2 V | 39.6 kΩ / 2.8 V |
| Room temp. | CN8 | 33.6 kΩ / 1.1 V | 12.5 kΩ / 2.2 V | 8.0 kΩ / 2.8 V |
Ticket wording
Record the actual bulb temperature and resistance, not just pass/fail. Example: “Outdoor thermistor measured 12.7 kΩ at approximately 20°C; within expected 12.6 kΩ.”
8. Indoor fan motor checks
| Step | Check | Expected / decision |
|---|---|---|
| 1 | Power off. Rotate fan wheel by hand. | Fan should rotate freely. If caught, dropped, locked or bearing noisy, replace fan/motor as applicable. |
| 2 | Check ambient around motor. | If excessive heat from surrounding equipment, allow to cool and retest. |
| 3 | ARTG30/36 CN105 DC fan motor terminal reference. | Pin 1 Red = Vm / motor power; Pin 4 Black = GND; Pin 5 White = Vcc; Pin 6 Yellow = Vsp; Pin 7 Brown = PG. |
| 4 | Power-off resistance/short check. | Circuit-test Vm to GND. If shorted below 300 kΩ, replace fan motor and relevant PCB. |
| 5 | Live qualified check only. | Manual PCB notes show DC340 V motor power plus DC15 V / DC13.5 V / DC12 V / DC5 V control circuits. Use extreme care. |
| 6 | If fan rotates and readings are normal but error remains. | Follow manual path: inspect connector and harness, then power supply PCB/controller PCB depending on model and fault. |
9. Outdoor fan motor checks
Training warning
Do not disconnect a DC brushless fan motor while power is applied. The training material warns that resistance readings can be misleading on DC brushless fan motors; use the manual’s Vm-GND short check and diode-test/control checks.
| Step | Check | Expected / decision |
|---|---|---|
| 1 | Power off. Rotate fan by hand. | Should rotate freely without catching or bearing noise. |
| 2 | CN800 terminal reference | AOTG30: Pin 1 Red Vm, Pin 4 Black GND, Pin 5 White Vcc, Pin 6 Yellow Vsp, Pin 7 Brown FG/PG. AOTG36/45 follow the same function set. |
| 3 | Power-off short check | Measure Vm to GND. If shorted below 300 kΩ, replace outdoor fan motor and main PCB. |
| 4 | Live qualified check | Confirm motor power and control voltage only if safe. The manual shows DC340 V motor power and DC15 V control supply on the outdoor fan circuit. |
| 5 | If motor tests pass | Check outdoor PCB drive, fan command, connector pins, corrosion and error recurrence. |
10. Electronic Expansion Valve (EEV) - readings and decision tree
Manual operating logic
The EEV is driven as a DC stepper coil. The service instruction states the valve is controlled from compressor frequency, discharge temperature and outdoor temperature. At power-up the valve initialises by driving toward the closing direction.
| Model | Connector | Measure | Expected value |
|---|---|---|---|
| AOTG30LBTC | CN700 Expansion Valve Coil | Red common to Blue / Orange / Yellow / White | 46.0 Ω at 20°C each winding |
| AOTG36LBTC / AOTG45LBTC | CN111 Expansion Valve Coil | Red common to Blue / Orange / Yellow / White | 46.0 Ω at 20°C each winding |
| All models | PCB drive | DC drive during initialisation / operation | Valve should initialise at power-up; confirm drive/noise before condemning valve body. |
| Phone support step | Instruction | Decision |
|---|---|---|
| 1 | Ask technician to isolate power, wait for discharge and unplug EEV coil connector. | Do not ohm-test with connector still connected to PCB. |
| 2 | Measure Red to each phase wire. AOTG30 uses CN700. AOTG36/45 uses CN111. | All phase readings should be close to 46 Ω at 20°C. Uneven/open/short = coil fault. |
| 3 | Reconnect coil and power up. Ask whether valve makes initialisation/stepping noise. | No movement with correct coil may indicate missing PCB drive, wiring/connector issue or stuck valve. |
| 4 | If refrigeration symptom remains, check pipe temperatures across the valve and strainer. | Closed/restricted valve can show abnormal temperature difference. Open valve normally has little/no difference at the correct point in the cycle. |
| 5 | Before ordering parts, record resistance, connector photos, power-up behaviour and operating pressures/temperatures. | This prevents ordering EEV coil for what is actually a strainer, charge, sensor or PCB issue. |
11. Pressure sensor / pressure switch checks
| Model | Component | Test | Expected / note |
|---|---|---|---|
| AOTG30LBTC | High pressure switch | Continuity/contact check and circuit proof. | AOTG30 refrigerant diagram shows high pressure switch but not the pressure sensor used on 36/45. |
| AOTG36LBTC / AOTG45LBTC | Pressure sensor + high pressure switch | Confirm 5 V DC supply, ground and Vout return. | Training example: 1.14 V return equals approximately 800 kPa. Compare return voltage to actual gauge pressure. |
| All models | Pressure fault | Check actual refrigeration condition before replacing sensor. | Confirm fans, coil condition, charge, valves open, airflow and EEV/strainer before PCB/sensor. |
12. Compressor checks
Do this before condemning inverter/ACTPM
A compressor fault can present like an IPM/inverter fault. The compressor windings and insulation must be proven before ordering PCB parts.
| Model | Winding test | Expected | Fail action |
|---|---|---|---|
| AOTG30LBTC | U-V / V-W / U-W | 0.642 Ω at 20°C and all three balanced | If open, short, unbalanced or poor insulation to earth, replace compressor. |
| AOTG36LBTC / AOTG45LBTC | U-V / V-W / U-W | 0.432 Ω at 20°C and all three balanced | If open, short, unbalanced or poor insulation to earth, replace compressor. |
| All models | Insulation to earth | Training benchmark: > 1 MΩ from each winding to earth | If low, compressor is suspect. Do not fit PCB until compressor risk is resolved. |
| Symptom | Phone checks | Decision |
|---|---|---|
| Does not start | Open/loose compressor cable, winding resistance, gas valve open, DC bus and inverter command. | If wiring and winding normal, then proceed to inverter/IPM checks. |
| Stops soon after starting | Valve open, refrigerant leak, low pressure, strainer restriction, compressor winding and insulation. | If refrigerant circuit normal and compressor proven, proceed to inverter/IPM. |
| Abnormal noise | Loose bolts, pipe contact, vibration, internal compressor noise. | Separate installation/vibration noise from internal compressor defect. |
13. IPM / ACTPM / inverter power checks
| Check | Expected | Decision |
|---|---|---|
| AC supply into outdoor | Correct 240 V single phase supply and polarity. | Correct supply issue first. |
| DC IN / DC bus | Training benchmark: 330-380 V DC. | If AC present but no DC, check relay, diode bridge, ACTPM, capacitor/filter PCB and shorted DC loads. |
| ACTPM power-off resistance | Black lead “-”, red lead “+”: 360 kΩ. Black “-” to L1: 360 kΩ. Black “-” to L2: over 1 MΩ. Black “-” to N: 0 Ω. Black “+” to P: 720-900 kΩ. Black “N” to P: 360-540 kΩ. | If shorted/burnt/outside expected range, ACTPM may be faulty. Disconnect control harnesses during power-off tests. |
| Visual PCB condition | Burn marks, cracked components, water ingress, insect contamination, loose connectors. | Photograph before disturbing. |
| Load isolation | Disconnect suspect loads only when isolated and safe. | Shorted fan/EEV/compressor can damage replacement PCB if not identified. |
14. Bridge rectifier / diode bridge checks
| Power-off diode-test path | Expected reading |
|---|---|
| Black lead to +, red lead to each ~ terminal | Approximately 0.4 V each |
| Black lead to each ~ terminal, red lead to - | Approximately 0.4 V each |
| Black lead to +, red lead to - | Approximately 0.7-0.9 V |
| Black lead to -, red lead to + | OL |
Decision
A short or open diode bridge can cause no DC bus or breaker trip. Recheck downstream DC loads before replacing the board.
15. 4-way valve checks
| Check | Expected / decision |
|---|---|
| Mode command | On this AC valve style, the 4-way valve is powered throughout heating. |
| Voltage to coil | AC 240 V ON in heating. |
| Coil resistance | 1355 Ω ±10% at 20°C. |
| Pipe temperature change | Confirm refrigerant reversal by pipe temperatures. If coil energises but no change, valve may be stuck. |
| No coil voltage | Check PCB output, connector and harness. |
16. Drain / float switch
| Step | Check | Decision |
|---|---|---|
| 1 | Confirm actual water level, drain fall, blockage, trap, pump and safety drain condition. | Rectify site drainage before part replacement. |
| 2 | Check float switch connector and cable. | Loose/open cable can trigger drainage fault. |
| 3 | Lift/lower float and verify switch state changes. | If no change, replace float switch. |
| 4 | If float and drain are good but error remains. | Check indoor PCB input path. |
17. Defrost and no-code performance checks
| Symptom | Checks | Likely path |
|---|---|---|
| Poor heating / frequent defrost | Outdoor coil blocked, fan operation, outdoor thermistor, heat exchanger thermistor, charge and airflow. | Thermistors, fan, pressure, EEV and charge verification. |
| High discharge / compressor temp | Indoor filters/coil, outdoor coil, fan, EEV, charge, discharge thermistor. | Thermistor + EEV + airflow + refrigerant checks. |
| Low pressure / freeze protection | Indoor airflow, blocked coil/filter, low charge, EEV/strainer restriction, pressure sensor. | Pressure and EEV checks. |
| No code poor performance | Static pressure, ducting, air balance, ambient, set point, mode, pipe length, charge and valves. | Collect photos/readings before warranty decision. |
18. Test run and pump down
| Function | Support instruction |
|---|---|
| Test run | Use the service menu/test run procedure from the service instruction. Test run stops after approximately 60 minutes or if cancelled. Record indoor fan, outdoor fan and compressor operation. |
| 3-minute restart prevention | If compressor has just stopped, wait at least 3 minutes before diagnosing no-start. |
| Pump down | Only coach qualified technicians. Confirm valves are open before start. Follow the outdoor display/button sequence. Close liquid valve at the specified stage, then gas valve at the specified stage. |
| Failed pump down | If error occurs, recover refrigerant from service port rather than continuing unsafe operation. |
19. Ticket evidence checklist
| Evidence item | Required detail |
|---|---|
| Model and serial | Indoor ARTG model, outdoor AOTG model and serial numbers. |
| Error evidence | Wired remote code, indoor LED pattern, outdoor LED/display pattern and photos before reset. |
| Power readings | Supply voltage, DC bus, terminal wiring photos and communication/remote readings. |
| Thermistors | Actual bulb temperature, resistance and live voltage if taken. |
| EEV | Connector number, Red-to-phase resistance values, power-up movement/noise and pipe/strainer temperature observations. |
| Fan motors | Rotation check, Vm-GND resistance/short check, connector photos and any control voltage readings. |
| Compressor | U-V, V-W, U-W resistance; insulation to earth; connector photos. |
| IPM/ACTPM/diode bridge | ACTPM values, diode test values, DC bus, visual PCB condition and photos. |
| Refrigeration evidence | Operating mode, ambient, pressures, pipe temperatures, coil/filter condition, airflow/static pressure where relevant. |
| Conclusion | What has been ruled out and why the proposed part/action is supported. |
Recommended closing language
Based on the readings provided, the next action is [repair/replace/check]. Please attach the meter readings and photos to the ticket before ordering parts or submitting the warranty claim, as the claim may be reviewed against the service manual and component test evidence.
Source material matched: Service Instruction Manual AOTG30LBTC/AOTG36LBTC/AOTG45LBTC; Service Manual ARTG__LHTA - AOTG__LBTC; Service Agent Training component testing document. Designed for Freshdesk source view with inline formatting.