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Hitachi Yutaki M & Yutaki S fault 77

Indoor-LCD receiver communication failure

Heat pump

What it means

No Opentherm/Hlink communication for a continuous period of 10 minutes.

Likely causes

  1. No Opentherm/Hlink communication for a continuous period of 10 minutes
  2. Loss of Opentherm/Hlink communication for 10 minutes

Where to start

  1. Check Opentherm/Hlink communication link
  2. Check Opentherm/Hlink communication wiring between indoor and LCD receiver
  3. Check LED1 (Red) on PCB1 for Power status

The full answer, free

  • 8 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 336), 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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