F1, F2, F3, F4, F5 & L1 Fault Codes - Temperature and Humidity Sensor Troubleshooting Guide | LCHV BCHV WCHV KCHV


⚠️ Safety Notice – Reverse Cycle Air Conditioners

This equipment must only be installed, commissioned, serviced and repaired by suitably qualified and licensed personnel.


Before commencing work, complete a task-specific risk assessment and ensure electrical isolation procedures, safe access, adequate service clearances and appropriate PPE have been considered. All work must comply with applicable regulations, standards and manufacturer requirements.


Particular care must be taken when working around electrical systems, refrigerant circuits, moving parts, roof spaces, ceiling spaces, confined spaces and working-at-heights hazards where applicable.


Do not proceed if safe access, required clearances, confined space risks or appropriate safety controls cannot be achieved and maintained. 


Safety takes priority over diagnosis, repairs, installation schedules and customer expectations. If the task cannot be completed safely, it must not proceed until the risks have been adequately controlled.


 

F1, F2, F3, F4, F5 & L1 Temperature and Humidity Sensor Faults

LCHV / BCHV / WCHV / KCHV Series Reverse Cycle Inverter Systems


Applicable Models

High Wall Split Systems

  • KSHV / KCHV Series
  • BSHV / BCHV Series
  • LSHV / LCHV Series
  • WSHV / WCHV Series

Inverter Ducted Systems

  • SDHV / SCHV Series

Cassette Systems

  • SBHV / SCHV Series

Multi Systems

  • MSHV / SCHV Series
  • MDHV Series
  • MBHV Series

Fast Technician Reference

Code RangeArea to Check First
F1–F5, L1Sensors and wiring
E6, UF, P6Communications wiring
E1, E3, E4, F0Refrigeration circuit
H3, H5, E5Compressor and inverter
PH, PL, HCPower supply
L3, LA, P8Outdoor fan and airflow
EE, P7, C5PCB faults

Fault Code Summary

Fault CodeFault DescriptionSensor Type
F1Indoor Ambient Temperature Sensor Fault15K NTC
F2Indoor Coil / Evaporator Temperature Sensor Fault20K NTC
F3Outdoor Ambient Temperature Sensor Fault15K NTC
F4Outdoor Coil / Condenser Temperature Sensor Fault20K NTC
F5Outdoor Discharge Temperature Sensor Fault50K NTC
L1Temperature & Humidity Sensor Fault100K NTC

Symptoms

The system may exhibit one or more of the following:

  • Unit will not start
  • Compressor stops operating
  • Indoor fan may continue running
  • Heating or cooling performance reduced
  • Fault code displayed on controller or indoor unit
  • Intermittent operation
  • Fault code returns after reset

Safety Notice

⚠️ Isolate power before disconnecting sensors or performing resistance measurements.

Resistance testing must be performed with the sensor disconnected from the control board to avoid inaccurate readings.

Troubleshooting Procedure

Step 1 - Inspect Sensor Connection

Check:

  • Sensor plug is fully inserted into the PCB
  • Loose terminals
  • Corrosion or moisture ingress
  • Damaged wiring
  • Pinched or crushed cables

Fault Found?

Yes

  • Repair connection.
  • Restore power and retest unit.

No

  • Proceed to Step 2.

Step 2 - Inspect Sensor Wiring

Check the entire harness between the sensor and PCB for:

  • Open circuit wiring
  • Damaged insulation
  • Short circuit to copper tubing
  • Short circuit to cabinet metalwork
  • Burnt connectors

Fault Found?

Yes

  • Repair or replace wiring.
  • Restore power and retest.

No

  • Proceed to Step 3.

Step 3 - Measure Sensor Resistance

Disconnect the sensor from the control board.

Using a multimeter, measure resistance across the sensor terminals.

Compare the reading to the applicable resistance table below.

Resistance Within Specification?

Yes

  • Proceed to Step 4.

No

  • Replace the sensor.
  • Restore power and confirm fault is cleared.

Step 4 - PCB Inspection

If:

  • Wiring is correct
  • Sensor resistance is correct
  • Connections are secure

The fault is likely caused by:

  • PCB input circuit failure
  • Dry solder joint
  • Control board fault

Action

Replace the relevant control board and retest.

Sensor Resistance Tables

F1 & F3 – Ambient Temperature Sensor (15K NTC)

Temp °CResistance kΩ
049.02
1029.90
2018.75
3012.07
407.97
505.38

F2 & F4 – Coil Temperature Sensor (20K NTC)

Temp °CResistance kΩ
065.37
1039.87
2025.01
3016.10
4010.62
507.17

F5 – Discharge Temperature Sensor (50K NTC)

Temp °CResistance kΩ
0161.0
1098.0
2061.48
3039.61
4026.15
5017.65

L1 – Temperature & Humidity Sensor (100K NTC)

Temp °CResistance kΩ
0357.92
10198.73
20124.96
3080.52
4053.14
5035.88

Quick Diagnosis Guide

Fault CodeSensor LocationMost Common Cause
F1Indoor ambient sensorLoose connector or failed sensor
F2Indoor evaporator sensorSensor disconnected or coil sensor failure
F3Outdoor ambient sensorDamaged outdoor sensor wiring
F4Outdoor condenser sensorSensor shorted to copper pipe
F5Outdoor discharge sensorFailed discharge sensor or damaged wiring
L1Indoor temperature/humidity sensorFailed humidity sensor or PCB fault

Repair Outcome

After repairs:

  1. Restore power.
  2. Clear any active alarms by power cycling the unit.
  3. Operate the system in heating and cooling modes.
  4. Confirm the fault code does not return.






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LCHV / BCHV / WCHV / KCHV Series Error Code Quick Lookup Table


Sensor Faults

CodeFault DescriptionSensor LocationLikely Causes
F1Indoor Ambient Temperature Sensor FaultReturn air sensorLoose connection, faulty sensor, damaged wiring, indoor PCB fault
F2Indoor Coil / Evaporator Temperature Sensor FaultIndoor coil sensorLoose connection, faulty sensor, damaged wiring, indoor PCB fault
F3Outdoor Ambient Temperature Sensor FaultOutdoor air sensorFaulty sensor, wiring short/open circuit, outdoor PCB fault
F4Outdoor Coil / Condenser Temperature Sensor FaultOutdoor coil sensorFaulty sensor, wiring short/open circuit, outdoor PCB fault
F5Outdoor Discharge Temperature Sensor FaultCompressor discharge pipeFaulty sensor, damaged wiring, outdoor PCB fault
L1Temperature & Humidity Sensor FaultIndoor humidity sensorFaulty sensor assembly, wiring fault, PCB fault
b5Gas Pipe Temperature Sensor FaultOutdoor refrigerant pipeSensor failure, short circuit, PCB fault
b7Gas Valve Temperature Sensor FaultRefrigerant circuitSensor failure, damaged wiring, PCB fault
PFAmbient Temperature Sensor Fault (Drive Board)Outdoor drive boardFaulty sensor or drive PCB

Communication Faults

CodeFault DescriptionLikely Causes
E6Indoor ↔ Outdoor Communication FaultWiring fault, indoor PCB fault, outdoor PCB fault
UFIndoor Unit ↔ Display Board Communication FaultDamaged communication wiring, display board failure
P6Main Board ↔ Drive Board Communication FaultCommunication wiring fault, drive board fault
rFRF Module FaultRF module disconnected or faulty
E6 (Window Unit)Wired Controller Communication FaultWiring fault, controller fault, PCB fault

Compressor Protection Faults

CodeFault DescriptionLikely Causes
H3Compressor Overload ProtectionRefrigerant issues, airflow restriction, compressor fault
H5IPM ProtectionModule overheating, compressor issue, power supply problem
E1High Pressure ProtectionDirty condenser, blocked airflow, high refrigerant charge
E3Low Pressure ProtectionLow refrigerant charge, low pressure switch fault
E4High Discharge Temperature ProtectionRestricted airflow, blockage, sensor issue
E5AC Overcurrent ProtectionHigh current draw, compressor issue, supply voltage problem
L9High Power ProtectionExcessive system load
P5Over-Phase Current ProtectionCompressor electrical fault
U2Lost Phase ProtectionSupply phase loss or compressor fault
HECompressor Demagnetisation ProtectionCompressor or power module issue

Power Supply / Electrical Faults

CodeFault DescriptionLikely Causes
HCPFC ProtectionUnstable power supply, PFC circuit fault
PHDC Bus Voltage Too HighHigh supply voltage
PLDC Bus Voltage Too LowLow supply voltage
U3DC Bus Voltage DropUnstable power supply
LdLost Phase FaultPhase loss, compressor wiring issue
U1Phase Current Detection Circuit FaultOutdoor PCB fault

Outdoor Unit Faults

CodeFault DescriptionLikely Causes
L3 / LAOutdoor Fan Motor FaultFan motor failure, motor wiring fault, outdoor PCB fault
oEUndefined Outdoor Unit FaultExtreme outdoor conditions, sensor faults, PCB issue
U9Outdoor Unit Zero-Crossing FaultOutdoor PCB fault
P8Module Overheating ProtectionRestricted airflow, dirty coil, IPM overheating
FFOutdoor Photoelectric Sensor FaultSliding door obstruction or sensor fault

Compressor Starting & Synchronisation Faults

CodeFault DescriptionLikely Causes
LCStart-Up FailureCompressor starting fault, PCB fault
H7Compressor DesynchronisationCompressor failure, inverter control issue
U5Current Detection FaultLow refrigerant, PCB fault

Refrigeration System Faults

CodeFault DescriptionLikely Causes
F0Refrigerant Shortage ProtectionLow refrigerant charge, restriction, leak
PUCapacitor Charging FaultCapacitor or charging circuit fault
U74-Way Valve FaultFaulty valve, wiring issue, low voltage

PCB / Electronics Faults

CodeFault DescriptionLikely Causes
EEEEPROM FaultOutdoor PCB failure
P7Module Temperature Sensor Circuit FaultOutdoor PCB failure
C5Jumper Cap FaultMissing or damaged jumper, PCB fault
C4Outdoor Unit Jumper Cap FaultJumper missing or incorrectly fitted

Capacity & System Configuration Faults

CodeFault DescriptionLikely Causes
LPIndoor and Outdoor Unit MismatchIncorrect model combination, addressing issue
E7Mode ConflictMultiple indoor units calling for opposing modes (heat/cool)

Status Codes (Not Faults)

CodeMeaning
E2Coil Anti-Freeze Protection Active
E9Anti-Cold Air Protection Active
H1Defrost Cycle Active
High Temp Condenser ProtectionNormal protective operation
Anti-Freezing ProtectionNormal protective operation
High Temp Evaporator ProtectionNormal protective operation
Frost PreventionNormal protective operation