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Hitachi Yutaki M & Yutaki S fault 204

Indoor unit stops answering to main PC-ARFH2E

Heat pump

What it means

LCD-origin alarm: the indoor unit has stopped responding to the main PC-ARFH2E controller. Applies to YUTAKI S/SC (o).

Likely causes

  1. Loose, disconnected, broken or short-circuited connector
  2. Loose connector
  3. Disconnected connector
  4. Broken connector
  5. Pump not operating within operating range
  6. Blocked or restricted water circuit
  7. Air trapped in water pipes
  8. Clogged water strainer

Where to start

  1. Check connector condition between indoor unit and Master PC-ARFH1E
  2. Check connector between indoor unit and Main PC-ARFH2E for loose, disconnected, broken or short-circuited condition
  3. Check that the water pump of the space heating circuit works within the pump operating range

The full answer, free

  • 13 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 338), 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 Hitachi manual for the Yutaki M & Yutaki S. Check the model on the data plate before you order parts.

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