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T073

T073 — Outside Air Thermistor Failure Alert

Carrier · 38AP Air Handler

What does T073 mean?

The outside air thermistor has failed. Outside air temperature reset functionality will be disabled, but the unit will continue to run under normal set point control. Outdoor ambient lockout is also disabled. The alert resets automatically when the thermistor functions correctly.

Common Causes

  • Outside air thermistor failure
  • Wiring issue to the thermistor
  • Faulty control board

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    The unit should attempt automatic reset when the thermistor is functional.

  2. 2

    Check wiring and connections to the outside air thermistor.

  3. 3

    If the failure persists, the thermistor or control board may need replacement.

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

Related Faults

A051A051 — Circuit A, Compressor 1 Stuck On Failure AlarmA052A052 — Circuit A, Compressor 2 Stuck On Failure AlarmA053A053 — Circuit A, Compressor 3 Stuck On Failure Alarm
Source: Carrier 38AP Air Handler
Open Manual (Page 163)Search more codes in this manual