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ARTC / AOTD LCTU-LATT 3 Phase R410A 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 modelsAR*A36LCTU, AR*A45LCTU, AR*C45LCTU, AR*C54LCTU plus related AU/AB indoor variants listed in the service instruction.
Outdoor modelsAO*D36LATT, AO*D45LATT, AO*D54LATT, AOTD60LATT.
System typeR410A 3 phase single / simultaneous operation multi type. High static ducted ARTC content is prioritised.
Main sourcesARTC54LCTU Service Instruction and Service Agent Training component testing material.
PurposeProvide a Freshdesk-ready call guide with linked GREAT-style flowcharts, component tests, expected readings and ticket evidence requirements.

2. Error code quick reference

CodeManual fault descriptionPhone support action / linked test
00Wired remote controller error3 wire remote check
01Serial error - reverse transferCommunication split flow
13Serial error - forward transferCommunication split flow
02Room temperature thermistor errorThermistor testing
04Indoor heat exchanger thermistor middle errorThermistor testing
09Water drain errorDrain / float switch
06Outdoor heat exchanger outlet thermistor errorOutdoor thermistors
0AOutdoor temperature thermistor errorOutdoor thermistors
0COutdoor discharge pipe temperature thermistor errorOutdoor thermistors
0EHeat sink thermistor INV errorInverter heatsink
15Compressor thermistor errorCompressor thermistor
29Outdoor heat exchanger middle thermistor errorOutdoor thermistors
2DHeat sink thermistor PFC errorPFC heatsink
20Manual auto switch errorIntake / wiring checks
2APower supply frequency detection errorPower checks
17Over current protectionOver current flow
18CT errorCT / filter PCB
1ACompressor location detection errorCompressor location flow
1BOutdoor unit fan errorOutdoor fan motor
1FConnected indoor unit errorConnected indoor unit checks
2EINV errorInverter / IPM
12Indoor fan motor lock / rev. errorIndoor fan motor
0FDischarge temperature errorDischarge temp flow
24Excessive high pressure protection on coolingPressure / airflow
16Pressure switch / sensor errorPressure sensor / switch
2BCompressor temperature errorCompressor temperature checks
2FLow pressure errorLow pressure flow
33PFC PCB errorPFC PCB
30Refrigerant circuit address set-up errorAddress / DIP switch
31Master / slave set-up errorMaster/slave setup
32Number of connected indoor unit errorConnected indoor number
11Model distinction error indoorModel / PCB checks
19Active filter errorActive filter / PFC

3. Quick map

Symptom / error familyMost likely areaJump to
No operation / remote blankPower supply, remote cable, CN6/CN14 DC12 VRemote check
E:01 / E:13Indoor/outdoor serial communication AC70-130 VCommunication split flow
E:00 / wired remote errorY1/Y2/Y3 signal and indoor PCB remote supply3 wire remote flow
E:02 / E:04 / E:06 / E:0A / E:0C / E:15 / E:29Thermistor connector, resistance and PCB 5 V supplyThermistors
E:12 / E:1BFan rotation, obstruction, motor output voltage and PCB checksIndoor fan / Outdoor fan
E:17 / over currentAirflow, fan, compressor, inverter/IPM areaOver current flow
E:1A / compressor location detectionCompressor harness, winding, inverter PCBCompressor location flow
E:0F / E:2B3-way valve, EEV/strainer, fan/heat exchanger, thermistor, refrigerant chargeDischarge/compressor temp flow
E:2FLow pressure, fan/heat exchanger, EEV/strainer, pressure sensor, refrigerantLow pressure flow

4. GREAT-style linked flowcharts

E:01 / E:13 communication split flow

Serial reverse or forward transfer error / no indoor-outdoor communication
↓
↓
↓
Reverse transfer / outdoor signal path
Is the AC70-130 V signal present?
YES
Proceed to field cable / indoor-side checks. Look for noise, poor earth, or intermittent cable fault.
NO
Manual directs main PCB replacement only after wiring, noise and power are proven.
Forward transfer / indoor signal path
Is the AC70-130 V signal present?
YES
Signal is present. Confirm cable integrity, polarity, earth and intermittent noise before parts approval.
NO
Check indoor controller PCB and power PCB after field wiring and power checks are complete.
Communication follow-on checks
Important split: Do not approve boards from an E:01/E:13 communication error until power supply, earth, noise, terminal condition and AC70-130 V serial signal checks are recorded.

3 wire remote controller communication check flow

Wired remote controller 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 CN6 on AR*C36-54LCTU or CN14 on other indoor units, pins 1-3. If no DC12 V from indoor PCB, suspect controller PCB.
Y1-Y3 below 11.4 VDC
Check cable length, poor joints, wrong polarity, damaged 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 and 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 whether CN6/CN14 pins 1-3 have DC12 V.

E:17 over current protection flow - Outdoor unit

Over current protection after inverter compressor operation
↓
Check electrical component connections in the control unit for loose terminal, removed connector, incorrect wiring or open cable
↓
Check outdoor heat exchanger for blocked airflow, recirculation or clogging
↓
Check outdoor fan operation and fan motor output
↓
Check compressor winding resistance and harness condition
↓
Check inverter PCB / IPM area before approving board replacement
↓
Airflow / coil issue
Clear obstruction, clean coil, correct recirculation or fan issue before parts replacement.
Fan motor abnormal
Complete outdoor fan motor voltage checks before PCB recommendation.
Compressor abnormal
Record compressor winding and insulation readings before compressor approval.
Inverter/IPM abnormal
Escalate as inverter PCB/IPM only after component checks are recorded.
Important: For E:17, the manual lists connection failure, outdoor fan operation failure, outdoor heat exchanger clogging, compressor failure and inverter PCB failure. Prove airflow and compressor condition before recommending an inverter board.

E:1A compressor location detection flow - Outdoor unit

Compressor position / rotor location detection error
↓
Turn unit on and confirm whether abnormal compressor noise is present
↓
Isolate supply and visually inspect compressor harness, compressor terminals and inverter PCB connections
↓
Check compressor winding resistance U-V, V-W and U-W
↓
Check inverter PCB / IPM diode paths and terminal condition
↓
Abnormal compressor noise present
Record noise evidence and complete compressor / harness checks before recommending compressor.
Harness burnt, loose, open or miswired
Repair or replace affected harness or terminal connection, reset power and retest.
Compressor winding abnormal
Escalate as compressor fault after values are recorded.
Inverter/IPM path abnormal
Escalate as inverter PCB fault after values are recorded.
Important: For E:1A, physically inspect the compressor harness and terminals before moving to inverter PCB replacement.

E:0F discharge temperature / E:2B compressor temperature flow - Outdoor unit

Discharge or compressor temperature protection during compressor operation
↓
Primary check: suspect refrigerant leak / insufficient refrigerant first
↓
Check 3-way valves are fully open
↓
Check EEV operation / coil resistance and capillary or strainer restriction
↓
Check outdoor fan operation and heat exchanger for foreign matter, blocked fins or recirculation
↓
Check discharge or compressor 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, 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
PCB becomes suspect only after refrigerant, valves, EEV, airflow and thermistor are proven.
Important: Treat E:0F/E:2B as refrigerant and system-condition faults first. The most common causes are refrigerant leak, restriction, valves not fully open, fan/heat exchanger problems or thermistor error.

E:2F low pressure error flow - Outdoor unit

Low pressure protection / low suction pressure condition
↓
Check 3-way valves are fully open and pipework is not restricted
↓
Check outdoor fan operation, obstruction, recirculation and heat exchanger condition
↓
Check EEV operation and strainer temperature difference
↓
Check pressure sensor value against actual pressure
↓
Check refrigerant amount and leak condition
↓
Valve closed / restricted
Open valve fully, correct restriction and retest.
Airflow issue
Correct fan operation, blocked coil or recirculation before replacing parts.
EEV / strainer issue
Check EEV coil, start-up noise, DC12 V and temperature difference across strainer.
Sensor issue
Confirm pressure sensor voltage against actual pressure 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, pressure 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 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. If caller is not qualified or cannot identify terminals safely, stop at non-invasive checks and arrange authorised attendance.

SOP 2 - E:01 / E:13 serial communication

  1. Reset power and confirm if the communication error returns.
  2. Check earth and external noise sources such as harmonic equipment near power cable.
  3. Check interconnect, control unit connections, loose connector, open cable or mis-wiring.
  4. Check power: outdoor terminal 1-2 and L1-N, L2-N, L3-N should be AC198-264 V.
  5. Serial signal check: expected AC70-130 V swing at outdoor terminal 2-3.
  6. If reverse signal is abnormal after power/wiring/noise checks, main PCB becomes suspect.
  7. If forward signal is abnormal after power/wiring/noise checks, check indoor controller PCB and power PCB.

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. ARTC manual remote supply reference: DC12 V at CN6 pins 1-3 for AR*C36-54LCTU or CN14 pins 1-3 for other indoor units.
  3. Remove Y2 from the remote. Measure remote terminal Y2 to Y3: expected fluctuating 7-11 / 7-12 VDC pulse.
  4. Measure disconnected Y2 wire going to indoor unit to Y3: expected fluctuating 7-11 / 7-12 VDC pulse.
  5. 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 8.04 kΩ, 35C 6.51 kΩ, 40C 5.30 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. Discharge/compressor thermistor rough values include 0C 168 kΩ, 20C 63 kΩ, 40C 26.3 kΩ, 60C 12.3 kΩ, 80C 6.3 kΩ, 100C 3.4 kΩ, 120C 2.0 kΩ.
  6. With thermistor removed, check PCB supply: expected DC5.0 V at the thermistor connector.

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. Use component testing method for DC brushless fan motors: do not rely on resistance readings where diode test is required.
  3. Check motor plug wiring: high voltage DC, DC ground, 15 VDC control, speed signal and feedback signal.
  4. Do not disconnect fan motor plug with power applied.
  5. If motor tests OK and fault remains, controller/power PCB becomes suspect.

SOP 6 - Outdoor fan motor testing

  1. Power off. Rotate fan by hand and check obstruction, bearing lock, propeller fan looseness or fan guard contact.
  2. Check ambient around motor and heat exchanger airflow.
  3. Live output reference at PCB connector CN81/CN82: Red pin 1 to Black pin 3 = DC250-400 V; Black pin 3 to White pin 4 = DC15 V ±2 V.
  4. If output voltage is not correct, main PCB becomes suspect after motor and wiring are proven.
  5. Do not disconnect outdoor fan motor plug with power applied.

SOP 7 - EEV and strainer testing

  1. Check EEV connector CN17 for loose connector or open cable.
  2. Remove connector and check EEV coil resistance: White-Red, Yellow-Brown, Orange-Red and Blue-Brown = 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 for loose or incorrect wiring.
  2. Check winding resistance between U-V, V-W and U-W. ARTC manual value: 0.799 Ω at 25C.
  3. Insulation test from any winding to earth should be greater than 1 MΩ.
  4. If resistance is 0 or infinite, replace compressor.
  5. If compressor does not start or stops soon, also check gas pipe valve, refrigerant leak, strainer clogging and harness condition before compressor approval.

SOP 9 - IPM / inverter testing

  1. Isolate supply and discharge capacitors before testing.
  2. Inspect inverter PCB connections and compressor harness for heat, loose terminals or miswiring.
  3. Use diode test on IPM/inverter paths where accessible and record all readings.
  4. If compressor winding is normal but fault remains after harness and fan/airflow checks, inverter PCB becomes suspect.

SOP 10 - Filter / PFC / current sensor checks

  1. Use this for CT error, PFC PCB error, active filter error and no-signal follow-on checks.
  2. Check loose terminals, removed connectors, incorrect wiring and open cable in control unit.
  3. For CT error, check Filter PCB CN200 pins 1-3 forty seconds after compressor starts. Higher than 0.2 V indicates inverter PCB failure; lower than 0.2 V indicates filter PCB failure.
  4. Record power supply and all connector conditions before board approval.

SOP 11 - Pressure sensor / high pressure checks

  1. Check connector and wiring open/short condition.
  2. Compare pressure sensor value to actual system pressure.
  3. For high pressure protection, verify indoor/outdoor coil cleanliness, fan operation, air bypass/recirculation and refrigerant overcharge before PCB approval.
  4. Record actual pressure, voltage/sensor value and operating mode.

SOP 12 - Drain / float switch

  1. Check float switch operation and blockage by dust.
  2. Check loose contact at CN9 and shorted or pinched wire.
  3. Check drain hose for clogging, traps or poor fall.
  4. If checks do not improve symptom, controller PCB becomes suspect.

SOP 13 - Power checks

  1. Check breaker and site supply.
  2. Check outdoor terminal 1-2, L1-N, L2-N and L3-N for AC198-264 V.
  3. Check phase condition, terminal tightness, earth and voltage drop under load.
  4. Record all measured voltages before component approval.

SOP 14 - Multi / address / model setup checks

  1. Confirm connected indoor model combinations and total capacity are correct for outdoor unit.
  2. Check refrigerant circuit address, master/slave settings and number of connected indoor units.
  3. Check model distinction / indoor PCB setting.
  4. Reset power after correcting DIP switch or setting errors.

SOP 15 - No cooling / no heating

  1. Check indoor fan runs on high fan, filter is clean and indoor heat exchanger is not blocked.
  2. Check outdoor unit operation, air route obstruction and heat exchanger condition.
  3. Check valve position and whether indoor capacity suits room size and site load.
  4. Check pipe length/diameter, interconnect wiring and communication line.
  5. Check strainer, EEV, compressor, gas pressure and leak condition. Recharge by evacuation and weighed charge only.

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 readingsSupply voltage, communication signal, remote Y1/Y2/Y3 readings, fan motor output voltage, PCB 5 V / 12 V checks.
Component readingsThermistor kΩ and measured temperature, EEV coil Ω, compressor winding Ω, insulation result, inverter/IPM readings, filter/PFC readings.
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, filter/PFC, inverter PCB, main PCB or controller PCB.