Lennox iComfort SL18XC-01 Installer Setup Manual page 24

Table 1. Alert Codes and Troubleshooting
Alert
Priority Alert Text
Code
(Furnace / Air Handler / Outdoor Unit/ Equip­
ment Interface Module) The thermostat has
180 Critical
found a problem with the (furnace, air­hand­
ler or outdoor unit) outdoor sensor.
(Furnace) The furnace roll out limit switch is
200 Critical
open.
(Furnace / Air Handler) The system has lost
201 Critical communication with the (furnace or air­hand­
ler) indoor blower motor.
(Furnace / Air Handler) The unit size code
202 Critical for the (furnace or air­handler) and the size
of blower motor do not match.
(Furnace / Air Handler) The unit size code
203 Critical for the (furnace or air­handler) has not been
selected.
(Furnace) There is a problem with the fur­
204 Critical
nace gas valve.
(Furnace) The furnace gas valve relay con­
205 Critical
tact is closed.
(Furnace) The furnace gas valve 2nd stage
206 Critical
relay is faulty.
(Furnace) The furnace hot surface igniter is
207 Critical
open.
(Furnace) The furnace low pressure switch
223 Critical
is open.
507341-02
Critical alerts are displayed on Home (user) screen, in the Homeowner alert button, and in
the Installer alert button. Minor and Moderate alerts are found only in the Installer alert
button.
Steps to clear
In normal operation after control recognizes sensors, the alarm will be sent if valid temper­
ature reading is lost. Compare outdoor sensor resistance to temperature/resistance charts
in unit installation instructions. Replace sensor pack if necessary. At the beginning of (any)
configuration, furnace or air­handler control will detect the presence of the sensor(s). If
detected (reading in range), appropriate feature will be set as 'installed' and shown in the
'About' screen. The alarm/fault will clear upon configuration, or sensing normal values.
Correct the cause of roll out trip. Reset roll out switch. Reset power to clear. Test the fur­
nace operation. The alarm/fault clears after the furnace roll out switch is closed.
Lost communication with indoor blower motor. Possible causes include: power outage,
brown­out, motor not powered, loose wiring, condensation on air handler control without
cover on breaker. Problem may be on control or motor side. Cleared after communication
is restored.
Incorrect appliance unit size code selected. Check for proper configuring under Unit Size
Codes for Furnace/Air Handler on configuration guide or in installation instructions. The
alarm/fault clears after the correct match is detected following a reset. Remove the ther­
mostat from the system while applying power and reprogramming.
No appliance unit size code selected. Check for proper configuring under: Unit Size Codes
for Furnace/Air Handler on configuration guide or in installation instructions. Critical Alert.
The alarm/fault clears after the correct match is detected following a reset. Remove the
thermostat from the system while applying power and reprogramming.
Check gas valve operation and wiring. The alarm/fault clears after the issue is corrected.
Check wiring on control and gas valve. The alarm/fault clears after the issue is corrected.
Furnace will operate on 1st stage for the remainder of the heating demand. The alarm/fault
will clear after the issue is corrected. If unable to operate 2nd stage, replace control.
Measure the resistance of hot surface igniter. Replace the it if it is not within the specified
range found in IOM. The alarm/fault clears after the issue is corrected.
Check pressure (inches w.c.) of low pressure switch closing during a heat call. Measure
operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct
operation and restriction. The alarm/fault clears after the issue is corrected.
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