R-Pro › Field cases › Air conditioning
AC PCB (Main Board) Fault — Diagnosis and Replacement
Likely causes
Identify PCB symptoms (no power, relay click only, repeated error code)
Check: PCB input voltage = check rated ±10% (single-phase 220V / three-phase 380V). PCB output = check compressor/fan signal terminals. Visual = bulged capacitors, burnt traces, cracked solder. Insects/dust on board = suspect short. Inverter type = check IPM module for short (specialized tester or manual).
What to do: Replace PCB = original OEM or fully compatible part. Generic/non-OEM = inverter protection mismatch, compressor damage. Power-off + ESD wrist strap when replacing. After replacement, run learning/DIP switches per manual. Warranty applies only to OEM.
PCB replacement cost = residential typically USD 150–400. Inverter control PCB, main PCB, outdoor PCB = 3 separate boards. Diagnose location precisely before replacing. Within warranty (1–5 years) = free repair.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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