H0
Daikin External I/O or Option Board Error

Daikin system shows H0; abnormal operation of external input/output

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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

Faulty external control board, Incorrect wiring to external contacts, Shorted external input, Wrong option PCB installed

How to Fix / Troubleshooting

Safety first: Turn off power before working on control wiring.

Steps:

  • If an external on/off, window contact, or BMS interface is connected, temporarily disconnect it and see if the error clears.
  • Check for shorts or incorrect voltage on external input terminals.

Technician tasks:

  • Verify correct option PCB type and wiring per Daikin documentation.
  • Replace faulty option or interface boards.
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Repair Difficulty

Medium 3/5

Required Part

External Control / Option PCB
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