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Mitsubishi · Heat pump troubleshooting

Indoor board LED1 and LED2 both off - no power

What is going on

Nothing on the indoor unit or remote works and both LEDs on the indoor control board are dark.

Likely causes

  • No power to the outdoor unit
  • Faulty outdoor control board
  • No power reaching the indoor unit on S1-S2
  • Faulty indoor control board or blown fuse

Check in this order

  1. Warning: Line voltage present. Work only with proper PPE and meters rated for the circuit.
  2. Check voltage at the outdoor power terminal block. None = check the breaker and supply wiring.
  3. Check voltage between S1 and S2 at the outdoor terminal block. None = check the fuse on the outdoor board and its wiring.
  4. Check S1 to S2 at the indoor terminal block. None = check the indoor/outdoor wire for a wiring fault.
  5. If voltage is there, check the fuse on the indoor board and its connectors. If they are good, the indoor board is faulty.

Applies to: PEAD-RP35/50/60/71/100/125/140JA and JA(L) ducted indoor units (220-240 V models)

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Source: Mitsubishi Electric PEAD-RP35-140JA(L) Service Manual, 10-4 Troubleshooting by inferior phenomena, p.35. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.