Lennox S40 - Page 59

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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
240 Service Soon
GF Low Flame Current
- Run Mode
This could be either low ame current or a loss of ame while in run mode.
• Check micro-amperes of the ame sensor using thermostat or control board.
• Clean or replace the ame sensor.
• Measure voltage of neutral to ground to ensure good unit ground.
• Clean face of burner assembly.
• Conrm that the vent termination is properly installed and not re-circulating.
• Check for loose a wiring connection at gas valve.
NOTE: Refer to Service and Application Note H-14-06“ Flame Rectication In All Gas Furnaces” for additional
information.
Automatically clears
after a proper micro-
amp reading has been
sensed.
241
Service
Urgent
GF Flame Out of
Sequence-Still Present
Flame sensed without call for gas heating. Perform the following:
• Shut off gas.
• Check for a gas valve leak.
• Check for voltage to gas valve.
Replace the gas valve if needed.
Automatically clears
when a heat call ends
successfully.
250 Service Soon
GF Primary Limit
Switch Open
The furnace primary limit switch is open. If limit switch is not closed within three minutes, the unit will go into a
60 minute soft lockout (Watchguard mode). Perform the following:
• Check for high gas pressure.
• Check for low supply air. Low supply air due to being plugged or restriction in system (example: dirty air
lter or blockage in duct work).
• Check for proper ring rate on furnace.
• Check for non-functioning zone dampers.
NOTE: Limit trips will place the Lennox Smart Zoning system into non-zone mode.
NOTE: See ACC-14-01 for further details.
Automatically clears
when a heat call ends
successfully.
NOTE: If this issue
occurred on an Lennox
Smart Zoning system,
the eld will need to
manually activate the
zoning.
252 Service Soon
IU Discharge Air
Temperature High
A discharge air-temperature is high. Perform the following:
• Check temperature rise, air ow and input rate.
• Check for dirty air lter(s).
NOTE: See Service and Application Note ACC-14-01 for further details.
Automatically clears
when a heat call ends
successfully.
270
Service
Urgent
GF Flame Failed To
Ignite
The furnace is in Watchguard mode. The furnace igniter cannot turn on the ame. This is a ve strike
condition during a single demand.
• Check for proper gas ow.
• Ensure that igniter is lighting burner.
• Check ame sensor current.
• Check for dirty lters.
• Check for blocked cold end heater box or condensate drain and cracked hoses.
Automatically clears on
successful ignition.