Hitachi Air Conditioner Error Codes

Complete Diagnostic & Troubleshooting Guide

Communication Errors
01
Indoor Unit Communication Error
  • Turn off power and restart system.
  • Inspect indoor–outdoor wiring connections.
  • Check for loose or corroded terminals.
  • Replace control PCB if communication fails.
02
Outdoor Unit Communication Error
  • Inspect communication cable between units.
  • Ensure stable power supply to outdoor unit.
  • Check PCB connectors and wiring harness.
  • Replace outdoor control board if needed.
Sensor Errors
03
Room Temperature Sensor Failure
  • Inspect room sensor wiring and placement.
  • Test thermistor resistance.
  • Check for moisture or corrosion.
  • Replace sensor if readings are abnormal.
04
Evaporator Sensor Fault
  • Check evaporator sensor connection.
  • Test resistance values with multimeter.
  • Inspect sensor mounting on coil.
  • Replace faulty sensor if needed.
05
Condenser Sensor Fault
  • Inspect condenser sensor wiring.
  • Check sensor resistance values.
  • Ensure proper placement on coil.
  • Replace sensor if defective.
Fan System Errors
06
Fan Motor Abnormal Operation
  • Check fan blades for obstruction.
  • Inspect motor wiring connections.
  • Test fan motor operation.
  • Replace fan motor if malfunctioning.
Compressor Protection Errors
07
Compressor Overload Protection
  • Allow compressor to cool down.
  • Check refrigerant pressure levels.
  • Clean condenser coils for airflow.
  • Inspect compressor relay and capacitor.
System & Memory Errors
08
EEPROM Error
  • Power cycle the unit.
  • Inspect PCB for moisture or damage.
  • Check memory IC connections.
  • Replace main board if error persists.
Power System Errors
09
Power Supply Instability
  • Check voltage supply stability.
  • Inspect circuit breaker and wiring.
  • Use voltage stabilizer if needed.
  • Replace power board if faulty.
Drain System Errors
10
Drain Pump Issue
  • Inspect drain hose for blockage.
  • Check drain pump operation.
  • Clean drain pan and filter.
  • Replace pump if defective.
Important: Electrical and refrigerant-related repairs should only be performed by a certified HVAC technician.