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T411

T411 — Thermostat Y2 Input Activated without Y1 Activated

Carrier · Energy Recovery Ventilators

What does T411 mean?

The thermostat's Y2 input is activated while Y1 is not, causing the unit to run as if both Y1 and Y2 were on.

Common Causes

  • Bad thermostat
  • Incorrect thermostat wiring

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the thermostat wiring for Y1 and Y2.

  2. 2

    Inspect the thermostat itself for proper function.

  3. 3

    Ensure the thermostat is programmed correctly for the system.

  4. 4

    Reset the unit after verifying wiring and thermostat settings.

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

Related Faults

1 Fault CodeFault Code 1 — OVERCURRENT10 Fault CodeFault Code 10 — PANEL LOSS11 Fault Code11 Fault Code — ID RUN FAIL
Source: Carrier Energy Recovery Ventilators
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