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Mitsubishi Ecodan fault 5

LED2 on FTC is blinking

Heat pump

What it means

LED2 on the FTC control board is blinking, indicating wiring faults either between FTC and outdoor unit, or in the main remote controller wiring, depending on the state of LED1.

Likely causes

  1. 2 or more main remote controllers have been connected to the FTC
  2. Fault with main remote controller transmission/receiving circuit board
  3. Electrical noise causes interference with transmission/reception of data for main remote controller
  4. Faulty wiring between FTC and outdoor unit (when LED1 also blinking)
  5. Faulty wiring in main remote controller (when LED1 lit)
  6. Multiple indoor units wired to a single outdoor unit
  7. Short-circuited wiring in main remote controller
  8. Main remote controller failure

Where to start

  1. Only connect 1 main remote controller to 1 FTC indoor unit board
  2. Turn the power to the indoor unit OFF and then ON
  3. Power to both the indoor unit and outdoor units should be switched OFF then ON

The full answer, free

  • 29 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 53), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Mitsubishi manual for the Ecodan. Check the model on the data plate before you order parts.

Other Mitsubishi Ecodan fault codes