U8
Daikin
Indoor Unit Group Control / Central Control Communication Error
Daikin system with multiple indoor units shows U8; some units may not start or may shut down unexpectedly
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect wiring of centralized controller bus, Short or open circuit on central control line, Duplicate central address settings, Faulty central controller PCB
How to Fix / Troubleshooting
Safety first: Isolate power to all units and controllers before working on control wiring.
Steps:
- Identify the central controller (e.g., Daikin intelligent touch controller or centralized wired remote) and its communication bus.
- Check that the bus wiring polarity and terminal assignments match Daikin's diagram.
- Inspect for any parallel connections or T-joints that are not allowed by the installation manual.
Technician tasks:
- Measure bus resistance and continuity; locate and repair shorts or opens.
- Check address settings on each indoor unit and the central controller to avoid duplication.
- Temporarily disconnect the central controller; if the system runs normally, the controller or its wiring is suspect and may need replacement.
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Repair Difficulty
Hard
4/5
Required Part
Central Controller / Control Bus Wiring
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