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Mitsubishi Ecodan fault 15

When a PUHZ-FRP outdoor unit is connected, DHW or heating operation cannot run

Heat pump

What it means

The outdoor unit is set to prioritise air conditioner indoor unit operation over the cylinder unit, and in the main remote controller settings Electric heater (Heating) or Electric heater (DHW) is turned off, preventing DHW or Heating operation.

Likely causes

  1. Outdoor unit set to prioritize indoor unit of air conditioner over cylinder unit
  2. Electric heater (Heating) or Electric heater (DHW) turned off in main remote controller settings

Where to start

  1. Check main remote controller settings for Electric heater (Heating) and Electric heater (DHW)
  2. Check OUT1 (Water circulation pump 1, Space heating/cooling & DHW) at TBO.1 1-2, connector CNP1.
  3. Check OUT2 (Water circulation pump 2, Zone1) at TBO.1 3-4.

The full answer, free

  • 26 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 56), 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