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Mitsubishi · Heat pump

E4 Indoor unit not receiving from remote controller

Medium severity Mr. Slim PEAD-RP JA(L) ducted indoor unit

What the control is telling you

The indoor board has received nothing valid from the remote (or another indoor board) for 2-3 minutes. If both remotes are set to Sub, the remote shows E0 and the outdoor board LEDs show E4.

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

Likely causes

  • Remote controller wire loose or broken
  • Both remote controllers set to Sub (none set to Main)
  • Remote controller wired wrong, or wired to more than one indoor unit
  • Refrigerant address repeated in a group
  • Faulty remote controller
  • Faulty indoor control board (address 0 unit)
  • Electrical noise on the remote controller wire

Test and repair steps

  1. Check the remote controller wire at the remote and at the indoor terminal block for loose or broken connections.
  2. With two remotes, set one to Main and the other to Sub.
  3. Wiring limits total length 500 m max, up to 16 indoor units and 2 remotes per group; do not use multi-core cable with 3 or more cores.
  4. Run the remote controller self-diagnosis RC OK = remote is fine, cycle power and replace the indoor board if the code returns; RC NG = replace the remote; RC E3 or ERC = noise on the line - reroute the wire away from power cables.
  5. In group control, if a new indoor board does not fix it, check the board in the unit with refrigerant address 0.

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Source: Mitsubishi Electric PEAD-RP35-140JA(L) Service Manual, 10-3 Self-diagnosis action table, p.33. Summarized in our own words; check the original manual for your model.

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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.