Lennox XP14 Elite Series Installation Instructions Manual page 22

DEFROST BOARD DIAGNOSTICS
See table 10 to determine defrost board operational conditions and to diagnose cause and solution to problems.
Table 10. Defrost Control Board Diagnostic LEDs
DS2 DSl
Condition/Code Possible Cause(s) Solution
Green Red
1 Check control transformer power (24V).
No power (24V) to board terminals R 2 If power is available to board and LED(s) do not
OFF OFF Power problem and C or board failure.
light, replace board.
Simultaneous Unit operating normally or in standby
SLOW Flash Normal operation mode. None required.
Alternating SLOW 5-minute anti-short cycle Initial power up, safety trip, end of
None required (Jumper TEST pins to override)
Flash delay room thermostat demand.
Simultaneous Sensor being detected open or shorted or out of temperature range. Board will revert to time/
FAST Flash Ambient Sensor Problem temperature defrost operation. (System will still heat or cool).
Alternating Coil Sensor Problem Sensor being detected open or shorted or out of temperature range. Board will not perform
FAST Flash demand or time/temperature defrost operation. (System will still heat or cool).
ON Indicates that board has internal component failure. Cycle 24 volt power to board. If code does
ON Circuit Board Failure not clear, replace board.
FAULT and LOCKOUT CODES
(Each fault adds 1 strike to that code's counter; 5 strikes per code = LOCKOUT)
SLOW
OFF Low Pressure Fault
Flash
OFF ON Low Pressure LOCKOUT
SLOW
Flash OFF High Pressure Fault
ON OFF High Pressure LOCKOUT
SLOW Discharge Line Temperature
Flash ON Fault
FAST Discharge Line Temperature
Flash ON LOCKOUT
Fast
Flash Discharge Sensor Fault
OFF Discharge Sensor
LOCKOUT
1 Restricted air flow over indoor or
outdoor coil.
2 Improper refrigerant charge in
system,
3 Improper metering device installed or
incorrect operation of metering
device,
4 Incorrect or improper sensor location
or connection to system.
1 Remove any blockages or restrictions from coils
and/or fans. Check indoor and outdoor fan motor for
proper current draws.
2 Check system charge using approach and subcool-
ing temperatures,
3 Check system operating pressures and compare to
unit charging charts.
4 Make sure all pressure switches and sensors have
secure connections to system to prevent refrigerant
leaks or errors in pressure and temperature mea-
surements.
This model does not have a defrost line sensor, therefore this code is not applicable.
The XP14 series units does not use a defrost line sensor, However, a resistor is installed
OFF across pins P4-1 and P4-2. If the resistor is missing or damage then this fault code will be
displayed.
Fast
Flash This model does not have a defrost line sensor, therefore this code is not applicable.
Table 11. Sensor Temperature/Resistance Range
Sensor Temperature Range °F (°C) Resistance Values Range (ohms) Pins/Wire Color
Outdoor (Ambient) -35 to 120 (-37) to (48) 280,000 to 3750 3 and 4 (Black)
Coil -35 to 120 (-37) to (48) 280,000 to 3750 5 and 6 (Brown)
Note: Sensor resistance decreases as sensed temperature increases (see figure 26).
5750
m, 7450
lOO
90
8o
70 | 11775
60 |B 15425
50 _119975
26200
30 [] 34375
w
20 m46275
III
10 62700 85300
o I I
10000 30000 50000 70000 90000
RESISTANCE(OHMS)
Figure 26. Ambient and Coil Sensors
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505244M 04/08