Lennox S40 - Page 54

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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
120 Service Soon Unresponsive Device
There is a delay in the system component responding to the system. Typically this alert code does not cause
any operational issues and will clear on its own.
• This alert code is usually caused by a delay in the outdoor unit responding to the thermostat.
• Leaking voltage from strands within the bundle.
> Land only the R wire on the R terminal to load the bundle with 24VAC.
►Typically only the R wire needs to be landed to identify if voltage is leaking.
►If voltage is present checking the other wires is informational only but not needed.
►If voltage is not present checking the other wires one at a time would be needed.
> Check each loose wire in AC mode to C on circuit board.
►Good voltage is .03 -.3VAC leaking voltage is not the issue.
►Acceptable can be up to .7VAC with moderate success.
►Some units have worked with up to 1.2VAC with occasional success.
►Voltage over 1.2VAC needs to be addressed.
Automatically clears
after an unresponsive
system component
(device) responds to
any inquiry.
124
Information
Only –
Dealer
Equipment Lost
Communications
The thermostat has lost communication with a system component for more than three minutes. System
component has lost communication with the thermostat.
• Check the wiring connections between components.
• Ohm wires.
• Cycle power.
• Any component that is miss-wired may cause a false component code to be shown on system component.
• Disconnect all wiring to other system components and check communication one at a time.
NOTE: When using a oat switch, use isolation relay to break common wire to outdoor unit. For testing
purposes, remove oat switch from the circuit
This alert code stops all associated system operations and waits for a heartbeat message from the system
component that is not communicating.
Automatically clears
after communication
is re-established with
applicable system
component (device).
125
Service
Urgent
Control Hardware
Problem
There is a hardware problem on a system component control. There is a control hardware problem.
• In system using Lennox Smart Zoning, the system will remain in non-zone mode (all dampers open) for
ve minutes after priority condition no longer exist.
• In systems using a Equipment Interface Module, remove jumper if present on indoor unit between R and
W2.
• In systems using a PureAir S, the pure air control board jumper selector is missing.
If none of the above tips are applicable, then replace the control if the problem prevents operation and is
persistent.
Automatically clears
ve minutes after the
issue no longer exists.