Lennox S40 - Page 63

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Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting
E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system,
SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender
Alert
Code
Inverter
Flash
Code
Priority
Condition
Actual Displayed Alert
Text Under dealer control
center > Notications
Component or System Operational State and Troubleshooting Tip
How to clear
alert code
345
Service
Urgent
Relay O Failure
The O relay on the system component has failed. Either the pilot relay contacts did not close or the relay coil
did not energize.
• Possible O relay / stage 1 failure.
• Pilot relay contacts did not close or the relay coil did not energize.
• Replace system component (device) control.
If error is applicable to the Lennox variable capacity outdoor units, the outdoor control will need to be
replaced.
Automatically
clears after the fault
recovered following
reset.
346
Service
Urgent
AH HP Jumper Not
Removed
The heat pump conguration link is not cut on the air handler control.
• Conguration link not cut on air handler control.
• Cut O to R.
NOTE: This is only applicable when matching non-communicating heat pump with Lennox communicating
indoor unit.
Automatically clears
when the system
detects that the issue
no longer exists.
347
Service
Urgent
IU or EIM Relay Y1
Fault
• 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.
Automatically clears
after reset and Y1 input
sensed.
348 Service Soon ID Relay Y2 Fault
Possible cause for alert code 348 is Y2 relay on the applicable system component may have failed. Lennox
communicating thermostat sends a Y2 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
348. Either the furnace pilot relay contacts did not close or the relay coil did not energize.
• Possible Y2 relay / stage 2 failure.
• Furnace pilot relay contacts did not close or the relay coil did not energize.
• No input back to furnace or air handler control.
Automatically clears
when the system
detects that the issue
no longer exists.
349
Service
Urgent
GF IFC Error Check
Jumper O to R
• Only applicable in non-communicating mode.
• The O to R link on the furnace has been cut and could possibly cause a brown out.
• Might also result in low voltage to which would generate alert code as well.
• Conguration link R to O needs to be restored. Will need to restore link by hard-wiring the R to O terminals
on the terminal strip.
Automatically clears
when the system
detects that the issue
no longer exists.