Lennox iComfort SL18XC-01 Installer Setup Manual page 32

Table 1. Alert Codes and Troubleshooting
Alert
Priority Alert Text
Code
Air Handler / Equipment Interface Module).
421 Critical The heat pump defrost cycle has taken more
than 20 minutes to complete.
Compressor top cap switch exceeding
422 Moderate
thermal limit.
Moderate /
423 The inverter has detected a circuit problem.
Critical
The liquid line temperature sensor has mal­
424 Moderate
functioned.
Outdoor control has increased minimum
425 Minor compressor speed to allow for proper oil re­
turn due to low ambient temperature.
426 Critical Excessive inverter alarms
Moderate / The inverter has detected a DC peak fault
427
Critical condition.
Moderate / The inverter has detected a high main input
428
Critical current condition.
Moderate / The inverter has detected a DC link low
429
Critical voltage condition.
Moderate /
430 Compressor start­up failure
Critical
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
Voltage sensed on W output terminal when Y1 out is deactivated.
Check condenser fan motor, TXV, indoor unit blower motor, stuck reversing valve or
clogged refrigerant filter. Automatically clears when error is corrected.
Control will lockout after 10 strikes within an hour. To clear disconnect power to outdoor
unit and restart.
In normal operation after outdoor control recognizes sensors, the alarm will be sent if valid
temperature reading is lost. Compare liquid line sensor resistance to temperature/resist­
ance charts in unit installation instructions. Replace sensor pack if necessary. At the be­
ginning 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 iComfort Wi­Fi thermostat 'About' screen. The alarm / fault will clear upon
configuration, or sensing normal values.
Outdoor ambient temperature is below system limit. Control will attempt to run at lowest
allowed compressor speed to allow for proper oil return. Automatically clears when out­
door ambient temperature rises above limit for more then 5 minutes.
After ten faults within one hour control will lockout. To clear disconnect power to outdoor
unit and restart. Inverter alarms 12 to 14 and 53 do not count towards this lockout condi­
tion.
If condition (55A or higher) is detected, outdoor unit will stop (compressor and fan).
Anti­short cycle is initiated. If peak current (55A or higher) occurs 10 times within an hour,
system will lockout. To clear, disconnect power to outdoor unit and restart.
If condition is detected, outdoor unit will stop (compressor and fan). Anti­short cycle is
initiated. If condition occurs 10 times within an hour, system will lockout. To clear, discon­
nect power to outdoor unit and restart.
Error occurs when DC link voltage drops below 14VDC. If condition is detected, outdoor
unit will stop (compressor and fan). Anti­short cycle is initiated. If condition occurs 10 times
within an hour, system will lockout. To clear, disconnect power to outdoor unit and restart.
If condition is detected, outdoor unit will stop (compressor and fan). Anti­short cycle is
initiated. If condition occurs 10 times within an hour, system will lockout. To clear, discon­
nect power to outdoor unit and restart.
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