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Comm.fault In

Comm.fault In — Communication fault with input card

Nibe · Ground Source Heat Pumps

What does Comm.fault In mean?

This alarm indicates missing communication with the input card (AA3). This blocks the relevant compressor, and if the heat pump is master, the supply is set to minimum.

Common Causes

  • Defective communication cables
  • Input card (AA3) malfunction

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check all communication cables and connections to the input card (AA3).

  2. 2

    Ensure cables are securely connected.

  3. 3

    If the problem persists, the input card may need replacement by a technician.

Browse all codes in this manual (49)
Verified technical data. Last updated: April 2026

Related Faults

Alarm bell in displayAlarm bell symbol in display — Malfunction detectedAlarm no. 54Alarm no. 54 — Motor protection breaker trippedAlarm numbers 70-99Alarm numbers 70-99 — Communication interrupted
Source: Nibe Ground Source Heat Pumps
Open Manual (Page 48)Search more codes in this manual