Lennox XC20-036-230-01 Installation And Service Procedure page 32

Table 6. Outdoor Control 7-Segment Display Alert Codes and Inverter LED Flash Codes
NOTE - System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification).
Only the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi
Inverter LED Flash
Code (number of
Alert Inverter
Code
Codes
Red LED
E 422 N/A N/A
E 423 40 4 flashes
E 424 N/A N/A
E 425 N/A N/A
E 426 N/A N/A
E 427 21 2 flashes
E 428 22 2 flashes
E 429 23 2 flashes
XC20
®
thermostat.
Priority
flashes)
Green LED
N/A Moderate
Moderate /
OFF
Critical
N/A Moderate
N/A Minor
N/A Critical
Moderate /
1 flash
Critical
Moderate /
2 flashes
Critical
Moderate /
3 flashes
Critical
Alarm Description
Compressor top cap switch
exceeding thermal limit.
The inverter has detected a
circuit problem
.
The liquid line temperature
sensor has malfunctioned.
Outdoor control has in­
creased minimum com­
pressor speed to allow for
proper oil return due to low
ambient temperature. NOTE -
Minimum speed adjustments
begin at 45°F and increase to
100% minimum at 17°F.
Excessive inverter alarms
The inverter has detected a DC peak fault condition. If condition (55A or higher) is detec­
ted, outdoor unit compressor and fan stop. Anti-short cycle is initiated. If peak current
(55A or higher) occurs 10 times within an hour, system is locked out. Indicates high pres­
sure, condenser fan failure, locked compressor rotor or overcharge. To clear, disconnect
power to outdoor unit and restart.
The inverter has detected a
high main input current con­
dition
.
On a call for compressor op­
eration, if DC link power in in­
verter does not rise above
180 VDC for 2 and 3 ton mod­
els, 250 VDC for 4 and 5 ton
models, within 30 seconds,
the control will display a mod­
erate code. If condition is de­
tected, outdoor unit will stop
(Compressor and fan). Anti-
short cycles is initiated. If
condition occurs 10 times
within a 60 minute rolling time
period, system will lock out
and display a critical code.
32
Possible Causes and Clearing Alarm
Issue: One of the wires from the top cap switch had pulled
off one of the TP terminals on the outdoor control board.
Corrective Action: Reconnected wire onto top cap ter­
minal.
Control locks out 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 is sent if valid temperature reading is
lost. Compare liquid line sensor resistance to temperat­
ure/resistance charts in unit installation instructions. Re­
place sensor pack if necessary. At the beginning of (any)
configuration, furnace or air­handler control detects the
presence of the sensor(s). If detected (reading in range),
appropriate feature is shown in the iComfort Wi­Fi
mostat About screen. The alarm / fault clears upon con­
figuration, or when normal values are sensed.
Outdoor ambient temperature is below system limit. Con­
trol attempts to run at lowest allowed compressor speed
to allow for proper oil return. Automatically clears when
outdoor ambient temperature rises above limit for more
than 5 minutes.
After ten faults within one hour, control is locked out, indic­
ating poor system operation. Review history of alarms to
resolve system setup. Check condenser fan motor, TXV,
indoor unit blower motor, over-charge, undercharge, or
clogged refrigerant filter.
To clear error, disconnect power to outdoor unit and re­
start. Inverter alarms 12 to 14 and 53 do not count toward
this lock out condition.
If condition is detected, is detected, outdoor unit com­
pressor and fan stop. Anti­short cycle is initiated. If condi­
tion occurs 5 times within an hour, system is locked out.
Indicates high pressure, condenser fan failure or over­
charge.
To clear, disconnect power to outdoor unit and restart.
Issues:
(1) If DC link power in inverter does not rise above 180
VDC for 2- and 3-ton models, 250 VDC for 4- and 5-ton
models, within 30 seconds, the outdoor control will dis­
play a moderate code.
(2) Capacitors on inverter do not properly charge.
Corrective Actions:
(1) check for proper main power to outdoor unit and for
any loose electrical connections.
(2) Outdoor control boards with part # 103686-03 have
software update to delay the de-energizing of the revers­
ing valve by four seconds when coming out of defrost.
®
ther­