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A174

A174 - ECB2 Board Communication Failure

Carrier · Air Conditioning

What does A174 mean?

Communication has failed with the Economizer Control Board 2 (ECB2). The entire unit will shut down.

Common Causes

  • Control board failure
  • Wiring error
  • Loss of power

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify power supply to the ECB2 board.

  2. 2

    Inspect all wiring connections to the ECB2 board.

  3. 3

    Contact a qualified technician for diagnosis and potential repair.

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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