HVAC Sales Master

Fault Code Lookup

HVAC Sales Master
Indoor unit not found
Wall control cannot find indoor unit on ABCD communication bus during initial Connex discovery/commissioning. COMMISSIONING-TIME DIAGNOSTIC — not a runtime fault. Appears during initial system setup, not during normal operation.
This code typically points to
  • ABCD wiring not connected between wall control and indoor unit
  • Indoor unit power not available during discovery
  • Wrong order of unit power-up during commissioning
  • ABCD polarity reversed (A swapped with B)
  • Open or shorted communication conductors
  • Failed indoor board preventing communication at startup
Next checks to confirm
  1. Verify 24V power at indoor unit board
  2. Verify ABCD wiring from wall control to indoor unit, correct polarity and landing
  3. Verify no shorts, opens, or high resistance on comm conductors
  4. Retry Connex discovery sequence from wall control
  5. If indoor still not found, escalate to indoor board diagnosis
Escalation
If wiring and power confirmed but indoor still not discovered, indoor board failure becomes likely.
Reset behavior
Clears when indoor unit is successfully discovered during next commissioning attempt.
Urgent
Fix now
Need deeper detail?
Retrieve the subcode for this platform:
  1. From the main screen, touch Menu
  2. Touch and hold the Service icon for at least 10 seconds until it turns green
  3. Open Service Information
  4. Use View Diagnostics for the most recent fault's top three likely root causes
  5. Use Last 10 System Events for timestamped recent events
  6. Use Run/Fault History for resettable fault counters, cycle counters, and run times
Source
Carrier/Bryant Infinity/Evolution Connex wall control installation instructions — commissioning/discovery section.
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