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INDOOR_UNIT_NOT_FOUND

Indoor Unit Not Found

Bryant · Air Conditioning

What does INDOOR_UNIT_NOT_FOUND mean?

The Evolution Control cannot detect the indoor unit. This communication error prevents the system from operating.

Common Causes

  • Incorrect or loose ABCD wiring to the indoor unit
  • Damaged communication wire
  • Indoor unit control board issue
  • Communication interference

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Recheck all ABCD wiring connections on the indoor unit and other system devices.

  2. 2

    Ensure wire colors are consistently matched at all terminals.

  3. 3

    Try pressing the left-side button to re-initiate detection.

  4. 4

    Disconnect all accessories and devices from the ABCD bus, then connect the User Interface directly to the indoor unit with a short wire to isolate the issue.

  5. 5

    Reconnect other devices one at a time to pinpoint the faulty component.

  6. 6

    Contact an HVAC technician if the problem persists.

Browse all codes in this manual (47)
Verified technical data. Last updated: April 2026

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Source: Bryant Air Conditioning
Open Manual (Page 16)Search more codes in this manual