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XP14 SERIES
Table 10. Defrost Control Board Description (XP14-XXX-230-01 through 07)
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 position P2 screw terminal block:
W1
24 VAC thermostat output for auxiliary heat operation
C
24 VAC system common
L
Service light thermostat connection
R
24 VAC system power input
Y2
24 VAC thermostat input for second stage compressor operation
O
24 VAC thermostat input for reversing valve operation
Y1
24 VAC thermostat input for first stage compressor operation
P3
Five position square pin header. P3 provides selection of the Y2 compressor lock-in temperature.
Note: This is applicable 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 temperature 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 temperature sensor.
DIS
(P4-1) Ground connection for discharge temperature 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 factory test connections.
Actuation
—When the reversing valve is de-energized,
the Y1 circuit is energized, and the coil temperature is
below 35°F (2°C), the board logs the compressor run time.
If the board is not calibrated, a defrost cycle will be initiated
after 30 minutes of heating mode compressor run time.
The control will attempt to self-calibrate after this (and all
other) defrost cycle(s).
Calibration success depends on stable system
temperatures during the 20-minute calibration period. If
the board fails to calibrate, another defrost cycle will be
initiated after 45 minutes of heating mode compressor run
time. Once the defrost board is calibrated, it initiates a
demand defrost cycle when the difference between the
clear coil and frosted coil temperatures exceeds the
maximum difference allowed by the control OR after 6
hours of heating mode compressor run time has been
logged since the last defrost cycle.
NOTE - If ambient or coil sensor fault is detected, the
board will not execute the TEST mode.
Termination
—The defrost cycle ends when the coil
temperature exceeds the termination temperature or after
14 minutes of defrost operation. If the defrost is terminated
by the 14-minute timer, another defrost cycle will be
initiated after 30 minutes of run time.
Each test pin shorting will result in one test event.
For
each TEST the shunt (jumper) must be removed for at
least one second and reapplied. Refer to flow chart as
illustrated in figure 20 for TEST operation.
Test Mode
—When Y1 is energized and 24V power is
being applied to the board, a test cycle can be initiated by
placing the termination temperature jumper across the
TEST pins for two to five seconds. If the jumper remains
across the TEST pins longer than five seconds, the control
will ignore the TEST pins and revert to normal operation.
The jumper will initiate one cycle per test.
Table 11. Sensor Temperature / Resistance Range
Sensor
Temperatur
e 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.
