Lennox XP14 Elite Series Installation Instructions Manual page 20

Table 9. Defrost Control Board Description
ID Description
O Out 24 VAC output connection for reversing valve
LO-PS Connection for low-pressure switch
Y2 24 VAC output for second stage compressor solenoid
Y1 24 VAC common output, switched for enabling compressor
contactor
HI-PS Connection for high-pressure switch
P1 Seven position square pin header. P1 provides selection of
the defrost terminate temperature based on the position of
selection shunt, as well as selection pins for enabling the
field test mode.
P2 The following connections are provided in the seven posi-
tion P2 screw terminal block:
Wl 24 VAC thermostat output for auxiliary heat op-
eration
C 24 VAC system common
L Service light thermostat connection
R 24 VAC system power input
Y2 24 VAC thermostat input for second stage com-
pressor operation
O 24 VAC thermostat input for reversing valve op-
eration
Y1 24 VAC thermostat input for first stage compres-
sor operation
P3 Five position square pin header. P3 provides selection of
the Y2 compressor lock-in temperature. Note: This is ap-
plicable for two stage compressor operations only.
P4 Six position square pin header. P4 provides connections for
the temperature sensors:
COIL (P4-5) Ground connection for outdoor coil tem-
perature sensor.
(P4-6) Connection for outdoor coil temperature
sensor
AMB (P4-3) Ground connection for outdoor ambient
temperature sensor.
(P4-4) Connection for outdoor ambient tempera-
ture sensor.
DIS (P4-1) Ground connection for discharge temper-
ature sensor.
(P4-2) Connection for discharge temperature
sensor. Note: This is applicable for two stage
compressor operations only.
P5 Two position square pin header. P5 provides selection of
the 30-second compressor delay option.
P6 Eight position header. P6 provides connections for the fac-
tory test connections.
Test: Defrost Temperature Termination Shunt
(Jumper) Pins--The defrost board selections are: 50, 70,
90, and 100°F (10, 21, 32 and 38°C). The shunt
termination pin is factory set at 50°F (10°C). If the
temperature shunt is not installed, the default termination
temperature is g0°F (32°C).
Note: The Y1 input must be active (ON) and the "0" room
thermostat terminal into board must be inactive.
DIAGNOSTIC LEDS
The state (Off, On, Flashing) of two LEDs on the defrost
board (DS1 [Red] and DS2 [Green]) indicate diagnostics
conditions that are described in table 10.
DELAY MODE
The defrost board has a field-selectable function to reduce
occasional sounds that may occur while the unit is cycling
in and out of the defrost mode. When a jumper is installed
on the DELAY pins, the compressor will be cycled off for 30
seconds going in and out of the defrost mode. Units are
shipped with jumper installed on DELAY pins.
DEFROST BOARD PRESSURE SWITCH
CONNECTIONS
The unit's automatic reset pressure switches (LOPS - $87
and Ht PS - $4) are factory-wired into the defrost board on
the LO-PS and Ht-PS terminals, respectively.
Low Pressure Switch (LO-PS)
When the low pressure switch trips, the defrost board will
cycle off the compressor, and the strike counter in the
board will count one strike. The low pressure switch is
ignored under the following conditions:
• during the defrost cycle and 90 seconds after the
termination of defrost
• when the average ambient sensor temperature is below
15 ° F (-9°C)
• for 90 seconds following the start up of the compressor
• during test mode
High Pressure Switch (HI-PS)
When the high pressure switch trips, the defrost board will
cycle off the compressor, and the strike counter in the
board will count one strike.
DEFROST BOARD PRESSURE SWITCH SETTINGS
• High Pressure (auto reset) - trip at 590 psig; reset at
418 psig.
• Low Pressure (auto reset) - trip at 25 psig; reset at 55
psig.
Low Ambient Thermostat Pins - P3 provides selection of
the Y2 compressor lock-in temperature. The XP14 series
heat pumps do not use a Y2 compressor and therefore
these pins are not active.
FIVE-STRIKE LOCKOUT FEATURE
The internal control logic of the board counts the pressure
switch trips only while the Y1 (Input) line is active. If a
pressure switch opens and closes four times during a Y1
(Input), the control logic will reset the pressure switch trip
counter to zero at the end of the Y1 (Input). If the pressure
switch opens for a fifth time during the current Y1 (Input),
the control will enter a lockout condition.
The five-strike pressure switch lockout condition can be
reset by cycling OFF the 24*volt power to the control board
or by shorting the TEST pins between 1 and 2 seconds. All
timer functions (run times) will also be reset.
If a pressure switch opens while the Y1 Out line is
engaged, a 5-minute short cycle will occur after the switch
closes.
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505244M 04/08