506468-01
Page 15 of 24
Issue 1946
ambient sensor is detected as being open, shorted or out
of the temperature range of the sensor, the board will not
perform demand defrost operation. The board will revert
to time/temperature defrost operation and will display the
appropriate fault code. Heating and cooling operation will
be allowed in this fault condition.
NOTE:
Within a single room thermostat demand, if 5-strikes
occur, the board will lockout the unit. Control board 24 volt
power “R” must be cycled “OFF” or the “TEST” pins on
board must be shorted between 1 to 2 seconds to reset
the board.
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 90°F (32°C).
Delay Mode
The defrost system 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.
NOTE:
The 30 second compressor delay feature (known
as the quiet shift)
must
be deactivated during any unit
performance testing. The feature is deactivated by
removing the jumper located on the compressor delay pins
Sensor
Temperature
Range
°
F (
°
C)
Red LED
(DS1)
Pins / Wire
Color
Outdoor
(ambient)
-35 (-37) to
120 (48)
280,000 to
3750
3 & 4
(black)
Coil
-35 (-37) to
120 (48)
280,000 to
3750
5 & 6
(brown)
Discharge (if
applicable)
24 (-4) to 350
(176)
41,000 to 103
1 & 2
(yellow)
NOTE
: Sensor resistance decreases as sensed temperature
increases.
Table 5. Sensor Temp. / Resistance Range
Coil Sensor
The coil temperature sensor considers outdoor
temperatures below -35°F (-37°C) or above 120°F (48°C)
as a fault. If the coil temperature sensor is detected as
being open, shorted or out of the temperature range
of the sensor, the board will not perform demand or
time/temperature defrost operation and will display the
appropriate fault code. Heating and cooling operation will
be allowed in this fault condition.
NOTE:
The coil temperature probe is designed with a
spring clip to allow mounting to the outside coil tubing. Coil
sensor location is important for proper defrost operation.
Ambient Sensor
The ambient sensor considers outdoor temperatures
below -35°F (-37°C) or above 120°F (48°C) as a fault. If the
Figure 8. Control Board
