Alert Code 347 — Relay Y1 Failure

What does 347 mean?

This critical alert occurs when the Lennox communicating thermostat requests compressor demand (Y1) but the indoor unit control does not detect 24VAC between Y1 and C terminals. This suggests a Y1 relay failure on the system component.

• Y1 relay failure on system component
• Furnace pilot relay contacts did not close
• Relay coil did not energize

Click steps to track your progress.

1. 1

   The system operation will stop.

2. 2

   The alert automatically clears after a reset and Y1 input is sensed.

3. 3

   If the problem persists, contact a qualified Lennox installer or service technician.