Field pattern: mini-split communication code comes back after a new board (interconnect wire and splices)
Communication codes are usually about the path between the boards, not the boards: loose or swapped terminals, a splice in the interconnect cable, solid or undersized wire, noise from nearby line-voltage runs, or a damaged cable. The wrong turn is replacing boards on the code alone; prove the interconnect first.
Cross-checked ~75 min moderateBrands: All
Before you start
- Many mini-splits carry line voltage on the interconnect terminals; treat them as live and verify zero voltage before touching
- Inverter boards hold a charge after power-off; wait the time stated on the unit before handling the outdoor board
- Refrigerant circuit work is BLOCKED: refer to an EPA 608-certified technician
Diagnostic steps
Unlock all 7 steps with expected values
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