Lennox XP19-024 User Manual

Page 18
TABLE 6
Defrost Control Board Diagnostic LEDs
DS2
Green
DS1
Red
Condition/Code Possible Cause(s) Solution
OFF OFF Power problem No power (24V) to board termi-
nals R & C or board failure.
1
Check control transformer power (24V).
2
If power is available to board and LED(s) do
not light, replace board.
Simultaneous
SLOW Flash
Normal operation Unit operating normally or in
standby mode.
None required.
Alternating
SLOW Flash
5−minute anti−short cycle
delay
Initial power up, safety trip, end of
room thermostat demand.
None required (Jumper TEST pins to override)
Simultaneous
FAST Flash
Ambient Sensor Problem Sensor being detected open or shorted or out of temperature range. Board will re-
vert to time/temperature defrost operation. (System will still heat or cool).
Alternating
FAST Flash
Coil Sensor Problem Sensor being detected open or shorted or out of temperature range. Board will not
perform demand or time/temperature defrost operation. (System will still heat or
cool).
ON ON Circuit Board Failure Indicates that board has internal component failure. Cycle 24 volt power to board. If
code does not clear, replace board.
FAULT & LOCKOUT CODES (Each fault adds 1 strike to that code’s counter; 5 strikes per code = LOCKOUT)
OFF SLOW
Flash
Low Pressure Fault
1
Restricted air flow over indoor
or outdoor coil.
2
Improper refrigerant charge in
t
1
Remove any blockages or restrictions from
coils and/or fans. Check indoor and outdoor
fan motor for proper current draws.
2
Ch k t h i h & b
OFF ON Low Pressure LOCKOUT
pp g g
system.
3
Improper metering device
installed or incorrect operation
pp
2
Check system charge using approach & sub-
cooling temperatures.
3
Check system operating pressures and
SLOW
Flash
OFF High Pressure Fault
i
ns
t
a
ll
e
d
or
i
ncorrec
t
opera
ti
on
of metering device.
4
Incorrect or improper sensor
location or connection to sys-
3
Ch
ec
k
sys
t
em opera
ti
ng pressures an
d
compare to unit charging charts.
4
Make sure all pressure switches and sensors
have secure connections to system to prevent
ON OFF High Pressure LOCKOUT
location
or
connection
to
sys
tem.
have
secure
connections
to
system
to
prevent
refrigerant leaks or errors in pressure and
temperature measurements.
SLOW
Flash
ON Discharge Line Tempera-
ture Fault
This code detects shorted sensor or high discharge temperatures. If the discharge
line temperature exceeds a temperature of 285ºF (140ºC) during compressor op-
eration the board will de
−
energize the compressor contactor output (and the de
-
FAST
Flash
ON Discharge Line Tempera-
ture LOCKOUT
era
ti
on,
th
e
b
oar
d
w
ill
d
e−energ
i
ze
th
e compressor con
t
ac
t
or ou
t
pu
t
(
an
d
th
e
d
e-
frost output if active). The compressor will remain off until the discharge tempera-
ture has dropped below 225ºF (107ºC).
OFF Fast
Flash
Discharge Sensor Fault The board detects open sensor or out of temperature sensor range. This fault is
detected by allowing the unit to run for 90 seconds before checking sensor resist-
ance If the sensor resistance is not within range after 90 seconds the board will
Fast
Flash
OFF Discharge Sensor
LOCKOUT
ance. If the sensor resistance is not within range after 90 seconds, the board will
count one fault. After 5 faults, the board will lockout.

Lennox XP19-024 Specifications

General

Brand	Lennox
Model	XP19-024
Category	Heat Pump
Language	English