Lennox iComfort SL18XC-01 Installer Setup Manual page 31

Table 1. Alert Codes and Troubleshooting
Alert
Priority Alert Text
Code
(Outdoor Unit) The discharge line temperat­
415 Critical ure has been consistently higher than the
recommended upper limit of 279ºF.
(Outdoor Unit) The outdoor coil sensor is
either open, short­circuited or the temperat­
416 Critical ure is out of sensor range. As a result the
outdoor unit control will not perform any de­
frost tempering.
(Outdoor Unit) The outdoor unit sensor is
either open, short­circuited or the temperat­
417 Critical ure is out of sensor range. As a result the
outdoor unit control will not perform any de­
frost tempering.
(Damper Control Module) The damper con­
trol discharge air temperature sensor is
Moderate either open, short­circuited or the temperat­
417
/ Critical ure is out of sensor range. As a result the
outdoor unit control will not perform any de­
frost tempering.
(Outdoor Unit) There is a faulty "W" output
418 Moderate
circuit.
(Outdoor Unit) The "W" output on the out­
door unit has reported more than 5 errors.
419 Critical
As a result, the system has shutdown the
outdoor unit.
(Outdoor Unit) The "W" output terminal on
420 Critical
the outdoor unit is not wired correctly
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
Discharge line high temperature error count reached five strikes. Make sure coil is clean
and airflow unobstructed in and out of condenser. Check system charge using approach
and sub cooling temperatures. Reset by putting outdoor board in test mode or resetting
low voltage power.
Sensor being detected open or shorted, or temperature is out of sensor range.
Outdoor unit control will not perform demand or time/temperature defrost operation. (Sys­
tem will still heat or cool.) Clears when outdoor unit control detects proper sensor read­
ings.
Outdoor unit control detects open or shorted sensor, or temperature that is out of sensor
range. Critical Alert after 10 minutes. Reset by replacing sensor. This fault is detected by
allowing the unit to run for 90 seconds before checking sensor resistance. If the sensor
resistance is not within range after 90 seconds, the board will count one fault. After 5
faults, the board will lock out. Check for proper sensor reading and attachment to line.
Replace if out­of­specifications.
The damper control module detects open or shorted discharge sensor, or temperature that
is out of discharge sensor range. Check the resistance of the discharge sensor and com­
pare to temperature resistance chart ­ replace if needed. Reset by replacing the discharge
sensor. This fault is detected by allowing the unit to run for 90 seconds before checking
discharge sensor resistance. If the discharge sensor resistance is not within range after
90 seconds, the control will count one fault. After 5 faults, the control will lock out. Check
for proper sensor reading and attachment to line. The alarm clears after a power reset.
W terminal is energized while in cooling mode. Possible cause may be a stuck closed
relay on the control, or something external to the control that is energizing W terminal
when it should not be energized. Solution: Disconnect any wiring from the W terminal. If 24
volts is still on the terminal, then it is a stuck relay. If the 24 volts disappears, then there is
a need to check any of the wires hooked up to the W terminal.
The W output (code E418) on the outdoor unit has reported more than five strikes. As a
result, the system has shut­down the outdoor unit. Disconnect thermostat lines from W
and verify 24VAC on the W. If 24VAC is present, replace the control.
Defrost cycle lasts longer than 20 minutes. Check heat pump operation. Cleared
when W1 signal is removed. Applicable only in communicating mode with non­communic­
ating heat pump.
31 iComfort Wi‐Fi
®
7-Day Programmable Communicating Thermostat