General Assist Technical Reference
J Series Troubleshooting & Error Codes
Indoor, outdoor and controller fault identification and diagnostic checks
Technical reference for J Series systems using receiver LEDs, outdoor PCB LEDs and remote-controller error codes.
How to use this article: Identify the fault from the indoor receiver, wired controller or outdoor PCB first. Then use the matching troubleshooting section below. Outdoor faults are commonly shown as E:32 at the indoor controller, so the outdoor PCB LED pattern is required to identify the specific outdoor fault.
Qualified service personnel only: These checks include live electrical measurements, refrigerant-system diagnosis and high-pressure components. Isolate power before disconnecting connectors or changing wiring. Refrigerant work must be carried out in accordance with applicable regulations and safe-work procedures.
1. Quick fault identification
Indoor receiver LED display
| Operation LED | Timer LED | 3rd LED | Fault |
|---|---|---|---|
| Continuous flash | Continuous flash | OFF | Model information error |
| Continuous flash | Continuous flash | Continuous flash | Power supply frequency error |
| Continuous flash | 4 flashes | 1 flash | EEPROM access error |
| 2 flashes | Continuous flash | OFF | Room temperature thermistor error |
| 3 flashes | Continuous flash | 1 flash | Heat exchanger inlet thermistor error |
| 3 flashes | Continuous flash | 2 flashes | Heat exchanger middle thermistor error |
| 4 flashes | Continuous flash | OFF | Drain error |
| 5 flashes | Continuous flash | 1 flash | Standard wired remote-controller error |
| 5 flashes | Continuous flash | 4 flashes | Standard wired token error |
| 6 flashes | Continuous flash | OFF | Indoor fan motor error |
| Continuous flash | 5 flashes | 1 flash | Serial signal error |
| Continuous flash | 3 flashes | 3 flashes | Outdoor unit error – identify fault at outdoor PCB |
Normal indications: In test run, the Operation and Timer lamps flash slowly together. During defrost or oil recovery the indoor fan may stop and the Operation lamp flashes slowly. A power-failure recovery can also produce alternating Operation/Timer indications depending on the auto-restart setting.
Outdoor PCB abnormal display
LED1 flashes rapidly during an outdoor fault. The number of flashes on LED2 to LED5 identifies the fault:
| PCB indication | Outdoor fault | Section |
|---|---|---|
| LED2 × 4 | Discharge temperature error | 2.1 |
| LED2 × 7 | High-pressure error | 2.2 |
| LED2 × 8 | Low-pressure error | 2.3 |
| LED2 × 9 | Pump-down error – high pressure | 2.4 |
| LED2 × 10 | Pump-down error – discharge temperature | 2.4 |
| LED2 × 11 | Pump-down error – other | 2.4 |
| LED3 × 1 | Discharge thermistor error | 3 |
| LED3 × 4 | Heat exchanger liquid thermistor error | 3 |
| LED3 × 6 | Heat exchanger middle thermistor error | 3 |
| LED3 × 10 | Suction thermistor error | 3 |
| LED3 × 11 | Outdoor temperature thermistor error | 3 |
| LED4 × 1 | Pressure switch 1 error | 2.5 |
| LED4 × 2 | Pressure switch 2 error | 2.5 |
| LED4 × 4 | Compressor rotor-location detection error | 2.6 |
| LED4 × 5 | Electric current trip | 2.6 |
| LED4 × 6 | CT error | 2.6 |
| LED4 × 9 | Trip terminal L start-up error | 2.6 |
| LED5 × 2 | Power-source frequency abnormal | 2.7 |
| LED5 × 3 | EEPROM error | 2.7 |
| LED5 × 7 | Microcomputer communication error | 2.7 |
| LED5 × 8 | Network communication error | 5 |
2. Indoor unit troubleshooting
| Code | Fault | Primary checks |
|---|---|---|
| E:02 | Model information error | Supply voltage/noise, connectors, PCB corrosion or damage; replace control PCB if required and restore original address/settings. |
| E:04 | Power supply frequency error | Check supply is 220–240 V, wiring/terminals, voltage drop, outages and electrical noise. Fault detection is below 45 Hz or above 66 Hz. |
| E:06 | EEPROM access error | Check power quality, connectors and control PCB. Replace control PCB if EEPROM access cannot be restored. |
| E:09 | Room temperature thermistor | Check connector/cable, thermistor resistance and 5 V PCB sensing circuit. |
| E:0A | Heat exchanger middle thermistor | Check thermistor wiring/resistance and 5 V sensing circuit. |
| E:0B | Heat exchanger inlet thermistor | Check thermistor wiring/resistance and 5 V sensing circuit. |
| E:11 | Drain abnormal | Float switch held ON for more than 3 minutes. Check float movement, CN15/wiring and control PCB. |
| E:13 | Indoor fan error | Check fan freedom, shaft/bearing, motor coil, motor temperature, output voltage and fan capacitor where fitted. |
| E:18 | Standard wired controller / token error | Check controller cable and terminals. On applicable ducted units, check CN17 controller supply: approximately DC 12 V indicates controller-side fault; 0 V indicates PCB/supply fault. |
| E:1F | Serial signal error | Check connection cable, communication PCB/connectors, F401, indoor PCB and power quality. If all indoor units are affected, continue with outdoor network communication checks. |
Indoor thermistor reference
| Thermistor | Approximate resistance |
|---|---|
| Room temperature | 0°C 33.6 kΩ; 5°C 25.2 kΩ; 10°C 20.1 kΩ; 15°C 15.8 kΩ; 20°C 12.5 kΩ; 25°C 10.0 kΩ; 30°C 8.0 kΩ; 35°C 6.5 kΩ; 40°C 5.3 kΩ; 45°C 4.3 kΩ; 50°C 3.5 kΩ. |
| Indoor heat exchanger inlet/middle | 0°C 176.0 kΩ; 5°C 134.2 kΩ; 10°C 103.3 kΩ; 15°C 80.2 kΩ; 20°C 62.9 kΩ; 25°C 49.6 kΩ; 30°C 39.5 kΩ; 35°C 31.7 kΩ; 40°C 25.6 kΩ; 45°C 20.8 kΩ; 50°C 17.0 kΩ. |
3. Outdoor unit troubleshooting
3.1 Discharge temperature error – LED2 × 4
Detection: Compressor stops three or more times after discharge-temperature protection is detected above approximately 118°C within 40 minutes. Protection is released when discharge temperature falls below approximately 93°C.
- Check refrigerant charge and leaks.
- Confirm discharge thermistor is correctly mounted and not open/cut.
- Check SV2 bypass valve and coil.
- Check outdoor fan and airflow.
- Check outdoor EEV and EV-KIT operation.
- Confirm service/3-way valves are fully open.
Leak-test reference from the service material: nitrogen sealing test pressure 600 psi / 4.15 MPa. The source notes that a 5°C ambient change can alter test pressure by about 10 psi / 0.07 MPa.
3.2 High-pressure error – LED2 × 7
Detection: Pressure SW1 opens at high pressure. The source specifies protection at more than approximately 609 psi / 4.2 MPa; repeated detection causes an error.
- Confirm all service/3-way valves are open.
- Check Pressure SW1 wiring, connector and switch.
- Confirm refrigerant charge is correct.
- Check outdoor fan operation and heat-exchanger airflow.
- Check outdoor EEV1 and EV-KIT.
- Check indoor fan operation and filter condition.
3.3 Low-pressure error – LED2 × 8
Detection: Pressure SW2 is detected OFF during compressor operation. Repeated low-pressure protection results in an outdoor fault.
- Confirm service valves are open.
- Check for refrigerant shortage/leak and correct charge.
- Check Pressure SW2 and its wiring.
- Check EEV1 and EV-KIT.
- Check outdoor fan and airflow.
- Check indoor fan/filter condition.
- Check outdoor-temperature thermistor and its mounting.
3.4 Pump-down errors
| Indication | Condition | Action |
|---|---|---|
| LED2 × 9 | High-pressure protection during pump down | Check valve position, Pressure SW1, charge, outdoor/indoor airflow, EEV1 and EV-KIT. |
| LED2 × 10 | Discharge temperature exceeds approximately 115°C during pump down | Check refrigerant, discharge thermistor, SV2, outdoor fan, EEV1/EV-KIT and gas-side valve position. |
| LED2 × 11 | Another protection/error occurs during pump down | Release pump-down mode and operate normally to identify the underlying fault. |
The service material notes that pump down may be unrecoverable depending on system refrigerant quantity and ambient conditions.
3.5 Pressure-switch input errors – LED4 × 1 / × 2
These faults are detected when the relevant pressure switch is already open at power-up.
- Check the relevant switch connector and cable for looseness or damage.
- Check the switch itself and verify operating pressure.
- Check the corresponding PCB input circuit for corrosion, damaged tracks or solder faults.
- Replace the switch or control PCB only after wiring and pressure conditions are verified.
3.6 Compressor, inverter and current-related faults
| Indication | Fault | Key checks |
|---|---|---|
| LED4 × 4 | Compressor rotor-location detection | CN15/CN16 between control and TR PCB, U/V/W wiring, compressor winding balance, TR PCB output balance and control PCB location-detection circuit. |
| LED4 × 5 | Electric current trip | Electrical connections, TR PCB/Control PCB, compressor insulation/continuity and balanced U-V/V-W/W-U output. |
| LED4 × 6 | CT error | CN202–CN11 wiring, Power PCB CT circuit (source gives approximately 560 Ω at CN11), diode bridge, reactor and TR PCB. |
| LED4 × 9 | Trip terminal L start-up error | CN14, TR PCB condition, control PCB IPM supply (approximately 15 V at CN16), trip-terminal circuit and compressor. |
Inverter testing: Disconnect power and discharge the DC bus before resistance/continuity testing of the TR/IPM section. When testing a running system, compare U–V, V–W and W–U outputs only using appropriate equipment and procedures.
3.7 Outdoor control / power faults
| Indication | Fault | Checks |
|---|---|---|
| LED5 × 2 | Power source frequency error | Frequency below 45 Hz or above 65 Hz for more than approximately 1 minute. Check supply, terminals, voltage, cable specification, electrical noise and Power PCB. |
| LED5 × 3 | Outdoor EEPROM error | Check 220–240 V supply, connection cable, voltage drop/noise, all connectors and control PCB condition. |
| LED5 × 7 | Microcomputer communication error | Check supply, cable/terminal integrity, electrical noise and outdoor control PCB. Restore any DIP settings after PCB replacement. |
4. Outdoor thermistor checks
For thermistor faults, first inspect the connector and wiring, then disconnect the thermistor and compare resistance with the reference table. If the thermistor is normal, check for approximately DC 5 V at the relevant PCB sensing circuit.
| Sensor | Connector | Part number in source | LED |
|---|---|---|---|
| Discharge temperature | CN21 | 9704219107 | LED3 × 1 |
| Heat exchanger liquid | CN22 | 9703306037 | LED3 × 4 |
| Heat exchanger middle | CN24 | 9900193010 | LED3 × 6 |
| Suction temperature | CN25 | 9900192013 | LED3 × 10 |
| Outdoor temperature | CN26 | 9900378035 | LED3 × 11 |
Discharge thermistor resistance
| Temperature °C | 0 | 5 | 10 | 15 | 20 | 30 | 40 | 50 | 60 | 70 |
|---|---|---|---|---|---|---|---|---|---|---|
| Resistance kΩ | 176 | 135 | 105 | 81.8 | 64.5 | 41.1 | 26.9 | 18.1 | 12.5 | 8.8 |
Additional discharge reference points: 80°C 6.3 kΩ; 90°C 4.6 kΩ; 100°C 3.4 kΩ; 120°C 2.0 kΩ; 140°C 1.2 kΩ; 160°C 0.8 kΩ; 180°C 0.5 kΩ.
Heat exchanger liquid / middle / suction thermistor resistance
| Temperature °C | -10 | -5 | 0 | 5 | 10 | 15 | 20 | 25 | 30 |
|---|---|---|---|---|---|---|---|---|---|
| Resistance kΩ | 27.5 | 20.9 | 16.1 | 12.4 | 9.7 | 7.7 | 6.1 | 4.9 | 3.9 |
Outdoor ambient thermistor resistance
| Temperature °C | -20 | -10 | -5 | 0 | 5 | 10 | 15 | 20 | 30 | 40 | 50 | 60 | 70 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Resistance kΩ | 105 | 58.2 | 44.0 | 33.6 | 25.9 | 20.2 | 15.8 | 12.5 | 8.0 | 5.3 | 3.6 | 2.5 | 1.8 |
5. Network communication error – LED5 × 8
The outdoor unit reports a network communication error when indoor-unit information cannot be received for approximately 20 seconds at start-up or during operation.
Do not branch the interconnection wiring. The source specifically shows branched indoor-unit connections, indoor units connected directly to the commercial supply instead of through the specified system arrangement, and branching from terminal boards as incorrect configurations that can blow fuses.
- Check outdoor-to-indoor connection cable polarity and terminal sequence.
- Check Outdoor Power PCB communication connector CN201.
- Check Outdoor Power PCB terminal TM203 (RED) and fuse F202.
- Check each indoor terminal block.
- Check indoor Communication PCB wiring and fuse F401.
- Complete address setting: power ON → perform each indoor-unit address setting → power OFF → power ON.
6. Remote controller diagnostics
Wired / simple remote controller
If E:EE flashes on the clock display, run self-diagnosis. The service material also provides functions to display the refrigerant-circuit address, indoor-unit address and up to 16 stored error codes.
- Stop air-conditioner operation before entering diagnostic mode.
- On the standard wired controller, the source uses the Set Temperature buttons with Start/Stop for address/history access, and a long press of the Set Temperature buttons for self-diagnosis/exit.
- On the simple controller, self-diagnosis uses Fan Control together with the Set Temperature buttons.
Controller variations: Button combinations differ between controller types. Confirm the controller model before instructing a customer or technician to enter service functions.
Common controller error-code reference
| Code | Typical meaning |
|---|---|
| 00 | No error |
| 02 | Model information abnormal |
| 04 | Power supply frequency abnormal |
| 06 | EEPROM access error |
| 07 | EEPROM deletion error |
| 09 | Room temperature thermistor |
| 0A | Heat exchanger middle thermistor |
| 0B | Heat exchanger inlet thermistor |
| 0C | Heat exchanger outlet thermistor |
| 0D | Blower temperature thermistor |
| 11 | Drain abnormal |
| 12 | Room temperature abnormal |
| 13 | Indoor unit fan error |
| 18 | Standard wired remote-controller communication error |
| 1F | Transmission error |
| 32 / outdoor error indication | Outdoor unit fault – read outdoor PCB LED pattern for the specific cause. |
7. Outdoor PCB normal-operation indicators
The outdoor PCB LEDs also show operating state when no fault is present. LED1 remains lit and LEDs 2–6 indicate conditions including cooling, heating, compressor-frequency range, pressure balance, oil recovery, defrost, test run, pump-down completion, SV1/SV2 open and compressor rotation-speed protection.
Important: A flashing outdoor PCB LED is not automatically a fault. Compare the flash rate and the active LED number with the normal-operation and abnormal-operation tables before replacing components.
8. Recommended diagnostic sequence
- Record the indication before resetting power. Capture controller code and indoor/outdoor LED pattern.
- Confirm supply and installation. Check voltage, terminals, loose wiring, breaker/cable condition and electrical noise.
- Check connectors and harnesses. Look for loose plugs, cut cables, corrosion, damaged tracks and incorrect connections.
- Check the sensor or actuator named by the fault. Use the resistance/voltage values above where provided.
- Check system conditions. Refrigerant charge, valve position, airflow, EEV operation and operating pressures can create protection faults without an electrical component being defective.
- Replace PCB/components only after the upstream checks are completed. Restore original address and DIP-switch settings after PCB replacement.
- Run and verify. Confirm normal operation and ensure the error does not recur under load.
Technical information condensed from the J Series troubleshooting service material. Refer to the applicable model service manual and wiring diagram before component replacement or live testing.