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A173

A173 - ECB1 Board Communication Failure

Carrier · Air Conditioning

What does A173 mean?

Communication has failed with the Economizer Control Board 1 (ECB1). The economizer and power exhaust will be stopped.

Common Causes

  • Control board failure
  • Wiring error
  • Loss of power

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure the ECB1 board is receiving power.

  2. 2

    Check all wiring connections to the ECB1 board.

  3. 3

    A technician must test the board and communication lines.

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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