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Heat pumps · Error codes · Hitachi
YCC-60Hitachi · Hitachi, all models

YCC-60 on a Hitachi heat pump: Slave unit alarm - all slave units in alarm state or no communication (YUTAKI Cascade Controller)

Short answer

On a Hitachi heat pump, YCC-60 means: Slave unit alarm - all slave units in alarm state or no communication (YUTAKI Cascade Controller). The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.

Reviewed 23 September 2026 · 1 source

What it means

The manual says: Slave unit alarm - all slave units in alarm state or no communication (YUTAKI Cascade Controller).

Part involved: YUTAKI Cascade Controller.

Likely causes:

  • Alarm on slave units / communication; released when the issue disappears.

Is it safe?

Does the heat pump stop?Partly
SeverityFault — clears by itself when the condition goes
Engineer needed?Yes

The heat pump keeps running with some functions stopped.

Resetting itself: yes - when issue disappears.

What you can check

  • Read and note the alarm code and any retry code (e.g. P70) shown on the unit controller.
  • Check the heat pump supply breaker/isolator at the consumer unit is ON.
  • Restart once via the unit controller (or switch off/on at the isolator) - the manual states the unit must be stopped to release most alarms; if the code returns, call an engineer.

What the engineer will check

  • Follow SMGB0146 section 6.7 troubleshooting flowchart for alarm 60.
  • Check H-Link / transmission wiring polarity, continuity and terminal tightness.
  • Check PCB fuses and DIP-switch/address settings.
  • Check power to the other unit (outdoor/indoor/controller).

Who to ask for: Heat pump installer / service engineer (controls wiring).

What you might notice

Sources

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026