H12
Panasonic Indoor Unit Capacity / Connection Mismatch

Multi-split system: one or more indoor units do not operate; H12 displayed on remote or indoor unit.

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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 indoor unit model combination, Wrong capacity setting on outdoor PCB, Incorrect wiring of indoor units to outdoor ports, Faulty outdoor PCB configuration memory

How to Fix / Troubleshooting

Safety first: Turn off power at the breaker before opening any covers.

Steps to check:

  • 1. Verify indoor unit models: Check the model numbers on all indoor units and compare with the outdoor unit's allowable combinations in the Panasonic installation manual. If an incompatible combination is installed, H12 will persist until corrected.
  • 2. Confirm piping and wiring ports: For multi-split systems, ensure each indoor unit's refrigerant piping and control wiring are connected to the same numbered port on the outdoor unit (e.g., indoor 1 to port 1, etc.).
  • 3. Check dip-switch or setting mode: Some Panasonic outdoor PCBs require capacity or port assignment settings via DIP switches or service mode. Verify these settings match the installed indoor units.
  • 4. Reset power: After corrections, power off the system for at least 5 minutes, then restore power and test again.

Note: If all combinations and settings are correct and H12 remains, the outdoor PCB configuration memory may be defective and should be replaced by a technician.

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Repair Difficulty

Hard 4/5

Required Part

Outdoor Control PCB
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