Lennox XC20-036-230-01 Installation And Service Procedure page 31

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
flashes)
Code
Codes
Red LED
E 345 N/A N/A
E 409 N/A N/A
E 410 N/A N/A
E 411 N/A N/A
E 412 N/A N/A
E 413 N/A N/A
E 416 N/A N/A
®
thermostat.
Priority Alarm Description
Green LED
Heat Pump or Air Conditioner
Alert Code - The "O" relay on
the outdoor board has failed.
Either the pilot relay contacts
did not close, the relay coil
N/A Critical
did not energize or the circuit
that confirms this operational
sequence is not sensing
properly.
Outdoor control secondary
N/A Moderate
voltage is 18VAC or less.
The outdoor unit cycled off
N/A Moderate due to low pressure switch
opening.
The low pressure switch has
opened 5 times within one
N/A Critical
hour. As a result, the outdoor
unit is locked out
The outdoor unit high pres­
N/A Moderate
sure switch has opened.
The high pressure switch has
opened 5 times within one
N/A Critical
hour. As a result, the outdoor
unit is locked out
The outdoor coil sensor has
Moderate malfunctioned.
N/A
/ Critical
the outdoor unit control will
not perform defrost.
Possible Causes and Clearing Alarm
Issue: Broken R50 will make the control board think re­
versing valve output is always off regardless of state of re­
lay. (Supplier issue - We have found our functional test fix­
ture can bend over MOV2 and crush it into R50.There are
cut-outs in the plate of the fixture to let the two relays pass
through as the plate with pogo pins is moved to the board
to make contact with the terminals. There is a pocket
milled out in the plate to let MOV2 pass, but if MOV2 is not
straight up, it could catch the plate outside the pocket and
be bent down to the board. Lennox is enlarging the cut-
outs in the plate so MOV2 will clear the fixture. Corrective
action completed on August 29,2013.
Corrective Actions: Short term fix: Converted the sys­
tem back to a 24 volt system to get unit operating. Long
term: Replace outdoor control.
Secondary voltage is below 18VAC. After 10 minutes, op­
eration is discontinued. Check the indoor line voltage and
transformer output voltage. The alarm clears after the
voltage is higher than 20VAC for 2 seconds or after a
power reset.
Unit pressure is below the lower limit. The system is shut­
down. The low pressure switch closes above 90PSIG and
opens below 40PSIG. Confirm that the system is properly
charged with refrigerant. Check TXV, indoor unit blower
motor, dirty filters or clogged refrigerant filter. Confirm that
the evaporator coil is clean. The alarm clears after the
pressure switch opens or after a power reset.
Low pressure switch error count reached 5 strikes. The
low pressure switch opens at 40PSIG and resets at
90PSIG. Confirm that the system is properly charged with
refrigerant. Check for clogged TXV, blockage to indoor
unit blower motor, dirty filters or clogged refrigerant filter.
.
Confirm that the evaporator coil is clean. The alarm clears
after a power reset.
Unit pressure is above the upper limit. System is shut
down. The high pressure switch opens at 590PSIG and
closes at 418PSIG. Confirm that the system is properly
charged with refrigerant. Check for clogged TXV, block­
age to indoor unit blower motor, clogged refrigerant filter.
Confirm that the outdoor unit is clean. The alarm clears
after the pressure switch closes or a power reset.
For heating, indoor CFM may be set too low. For zoning
system, zone CFM may be set too low.
Open high pressure switch error count reached 5 strikes.
System is shut down. The high pressure switch for
HFC­410A opens at 590PSIG and closes at 418PSIG.
Confirm that the system is properly charged with refriger­
ant. Check condenser fan motor, for clogged TXV, for
blockage to indoor unit blower motor, for stuck reversing
valve or clogged refrigerant filter. Confirm that the out­
.
door unit is clean. The alarm clears after a power reset.
For heating, indoor CFM may be set too low. For zoning
system, zone CFM may be set too low.
Coil sensor being detected open or shorted, or temperat­
ure is out of coil sensor range. Outdoor unit control will not
perform demand or time/temperature defrost operation.
As a result System is still able heat and cool. Check the resistance of
the coil sensor and compare to temperature resistance
chart. Replace coil sensor if needed. The alarm clears
when outdoor unit control detects proper coil sensor
readings or after a power reset.
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XC20