Lennox Error Code 347

Priority condition: Service Urgent • Lennox communicating thermostat sends a Y1 compressor demand to the indoor control requesting it to relay the demand to the outdoor unit. • The indoor unit communicating control will verify the presences of 24VAC between the Y1 and C on its terminals. If it does not detects the presences 24VAC, it will trigger alert code 347. Possible cause for alert code 347 is Y1 relay on the applicable system component has failed. Either the furnace pilot relay contacts did not close or the relay coil did not energize. • System operation will stop. • Possible Y1 relay / stage 1 failure. • Furnace pilot relay contacts did not close or the relay coil did not energize. NOTE: There is no input back to the applicable system component control.