F6
Mitsubishi Electric Indoor–Remote Controller Communication Error (wired controller models)

Indoor unit displays F6, system may not start or may stop unexpectedly

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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

Open or short in remote controller cable, Incorrect polarity or wiring, Faulty wired remote controller, Faulty indoor PCB communication port

How to Fix / Troubleshooting

Safety first: Turn off power before working on control wiring.

Steps:

  • Check wiring: Verify that the wired controller cable is connected to the correct terminals and that polarity is correct as per the wiring diagram.
  • Inspect cable: Look for cuts, pinches, or crushed sections along the cable route. Repair or replace as needed.
  • Test with spare controller: If available, connect a known-good wired controller directly at the indoor unit to rule out cable issues.
  • Replace controller or PCB: If the cable is good and F6 persists, replace the wired controller. If still unresolved, the indoor PCB communication port may be faulty.
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Repair Difficulty

Medium 3/5

Required Part

Wired Remote Controller
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