Lennox XC20-036-230-01

34
XC20
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
®
thermostat.
Alert
Codes
Inverter
Code
Inverter LED Flash
Code (number of
flashes)
Priority Alarm Description Possible Causes and Clearing Alarm
Red LED Green LED
E 436 62 6 flashes 2 flashes
Moderate /
Critical
Inverter heat sink temperat
ure exceeded limit. Occurs
when the heat sink temper
ature exceeds the inverter
limit. Inverter issues code
13 first, then slows down to
allow the heat sink to cool. If
temperature remains high,
outdoor unit stops (com
pressor and fan). Anti-short
cycle is initiated. If condition
occurs 5 times within an
hour, system is locked out.
To clear, disconnect power
to outdoor unit and restart.
Issue: Feedback from supplier tear down of inverter in
dicates that the screws that hold the inverter to the invert
er board were loose causing poor contact between these
two components.
Corrective Action: Tighten screws that hold the heat
sink to the inverter control board.
NOTE: Wait five minutes to all capacitor to discharge be
fore checking screws.
E 437 65 6 flashes 5 flashes
Moderate /
Critical
Heat sink temperature
sensor fault has occurred
(temperature less than 4ºF
or greater than 264ºF after
10 minutes of operation)
.
Occurs when the temperature sensor detects a temperat
ure less than 0.4ºF or greater than 264ºF after 10 minutes
of operation. If condition is detected, outdoor unit will stop
(compressor and fan). Antishort cycle is initiated. If con
dition occurs 5 times within an hour, system will lock out.
To clear disconnect power to outdoor unit and restart. If
problem persists, replace inverter.
E 438 73 7 flashes 3 flashes
Moderate /
Critical
The inverter has detected a
PFC over current condition.
This would be caused by a
high load condition, high
pressure, or outdoor fan fail
ure.Outdoor control will dis
play the code when the in
verter has the error. After 3
minutes, the inverter will re
set and the compressor will
turn on again. If it happens
10 times within a 60 minute
rolling time period, the OD
control will lock out opera
tion of the outdoor unit and
display a critical code.
Issue: Possible issue is system running at high pres
sures. Check for high pressure trips or other alert codes in
room thermostat and outdoor control.
E 439 12 1 flash 2 flashes Moderate
Compressor slowdown due
to high input current.
Input current is approaching a high limit. Compressor
speed automatically slows. The control continues send
ing the inverter speed demanded by the thermostat. The
control sets indoor CFM and outdoor RPM to values ac
cording to demand percentage rather than the actual Hz.
Alarm is automatically cleared.
E 440 13 1 flash 3 flashes Moderate
Heat sink temperature is
approaching limit. The
compressor speed auto
matically slows to reduce
heat sink temperature. The
control sets indoor CFM
and outdoor RPM to values
according to demand per
centage rather than the ac
tual Hz. Alarm is automatic
ally cleared.
Issue: Feedback from supplier tear down of inverter in
dicates that the screws that hold the inverter to the invert
er board were loose causing poor contact between these
two components.
Corrective action: Tighten screws that hold the heat sink
to the inverter control board.
NOTE: Wait 5 minutes to all capacitor to discharge before
checking screws.