Lennox S40 - Page 57

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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
223 Service Soon
GF Low Pressure
Switch Open
The furnace low pressure switch is open.
• Check pressure (inches w.c.) of the low pressure switch closing during a heat call.
• Measure operating pressure (inches w.c.).
• Inspect vent for blockages and combustion air inducer for correct operation and restriction.
• Check for blocked cold end heater box or condensate drain or drain strainers at outlet of cold end heater
box.
• Check for cracked hoses.
• Check levelness of unit.
NOTE: Check Service Manual and Service and Application Note H-13-07 “Condensing Furnace Pressure
Switch Troubleshooting” for additional information.
Automatically clears
after the issue is
corrected.
224
Service
Urgent
GF Low Pressure
Switch Stuck Closed
The furnace low pressure switch is stuck closed.
• Check operation of low pressure switch to see if it is stuck closed for longer than 150 seconds during a
heat call.
• Measure operating pressure (inches w.c.).
• Inspect vent for blockage and combustion air inducer for correct operation and restriction.
• Check for moisture in pressure switch.
NOTE: Check Service Manual and Service and Application Note H-13-07 “Condensing Furnace Pressure
Switch Troubleshooting” for additional information.
Other possible issues that are specic to the older Lennox communicating thermostats are as follows:
It has been determined that this alert code is generated when a subsequent heating call occurs within 30
seconds of a prior call for heat ending. If a call for heat occurs during this time period, the inducer post-purge
from the previous call may still be in process. If that condition exists, the IFC will sense the pressure switch
circuit is closed therefore activating the alert code 224 and generate an email notication. Once the fault is
cleared, typically seconds after being generated, the subsequent call for heat will be initiated and the furnace
will return to normal operation.
Lennox has not received any complaints of no heat situations associated with this operating condition. It has
been determined that occasionally the fault clears itself and the alert code is not stored in the IFC or Lennox
communicating thermostat.
Automatically clears
after the issue is
corrected.
225 Service Soon
GF High Pressure
Switch Failed to Close
The furnace high pressure switch will not close.
• Check pressure (inches w.c.) of high pressure switch closing during a heat call.
• Measure operating pressure (inches w.c.).
• Inspect vent for blockage and combustion air inducer for correct operation and restriction.
• Check for blocked cold end heater box or condensate drain or drain strainers at outlet of the cold end heater box.
• Check cracked hoses
• Check levelness of unit.
NOTE: Check Service Manual and Service and Application Note H-13-07 “Condensing Furnace Pressure Switch Troubleshooting” for
additional information.