Daikin Heat Pump Error Codes

Complete Heat Pump Diagnostics & Troubleshooting Guide

Refrigerant System Errors
U0
Low Refrigerant Level
  • Check for refrigerant leaks in system.
  • Inspect pressure levels with proper gauges.
  • Seal leaks before recharging refrigerant.
  • Call certified HVAC technician if needed.
Power Supply Errors
U2
Power Supply Voltage Issue
  • Check incoming power voltage stability.
  • Inspect circuit breakers and wiring.
  • Ensure correct electrical supply rating.
  • Use voltage stabilizer if necessary.
Communication Errors
U4
Signal Transmission Error
  • Inspect wiring between control boards.
  • Check connectors for looseness or corrosion.
  • Reset system after inspection.
  • Replace damaged communication cable.
U5
Indoor/Outdoor Communication Error
  • Verify cable connection between units.
  • Check for wiring damage or disconnection.
  • Restart both indoor and outdoor units.
  • Replace control board if fault persists.
Important: Heat pump systems involve high voltage and refrigerant handling—repairs should be done by qualified HVAC professionals.