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A172

A172 - Staged Gas Control Board 2 (SCB2) Comm Failure

Carrier · Air Conditioning

What does A172 mean?

Communication has failed with the second Staged Gas Control Board (SCB2). The cooling function will be stopped.

Common Causes

  • Incorrect wiring
  • Loss of power
  • Faulty control board

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify power to the SCB2 board.

  2. 2

    Check all wiring connections between the main control and SCB2.

  3. 3

    Contact a technician to diagnose the communication failure.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

A051A051 - Compressor 1 Stuck On FailureA052A052 - Compressor 2 Stuck On FailureA055A055 - Compressor 1 Stuck On Failure (Circuit B)
Source: Carrier Air Conditioning
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