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II − UNIT COMPONENTS
Unit components are illustrated in figure 2.
SPB*H4 UNIT COMPONENTS
FIGURE 2
OUTDOOR FAN
COMPRESSOR
HIGH PRESSURE
SWITCH
REVERSING
VALVE
FILTER
DRIER
CONTROL
BOX
EXPANSION
VALVE
VAPOR LINE
SERVICE
VALVE
LIQUID LINE
SERVICE
VALVE
LOW PRESSURE
SWITCH
A − Control Box (Figure 3)
SPB*H4 units are not equipped with a 24V transformer. All
24 VAC controls are powered by the indoor unit. Refer to
wiring diagram.
FIGURE 3
DUAL CAPACITOR
(C12)
COMPRESSOR
CONTACTOR
(K1)
UNIT CONTROL BOX
GROUNDING
LUG
DEFROST
CONTROL
(A108)
Electrical openings are provided under the control box cov-
er. Field thermostat wiring is made to a 24V terminal strip
located on the defrost control board located in the control
box. See figure 4.
FIGURE 4
C
R W1
O
Y1
L
24V THERMOSTAT TERMINAL STRIP
Y2
1 − Compressor Contactor K1
The compressor is energized by a contactor located in the
control box. See figure 3. Three−pole contactors are used
in all SPB*H4 series units. K1 is energized through the de-
frost control board by the indoor thermostat demand.
DANGER
Electric Shock Hazard.
May cause injury or death.
Disconnect all remote electrical power
supplies before opening unit panel.
Unit may have multiple power supplies.
2 − Dual Capacitor C12
The compressor and fan in SPB*H4 series units use perma-
nent split capacitor motors. The capacitor is located inside the
unit control box (see figure 3). A single dual" capacitor (C12) is
used for both the fan motor and the compressor (see unit wir-
ing diagram). The fan side and the compressor side of the ca-
pacitor have different MFD ratings. See side of capacitor for
ratings.
3 − Defrost Control
The demand defrost controller measures differential tem-
peratures to detect when the system is performing poorly
because of ice build−up on the outdoor coil. The controller
self−calibrates" when the defrost system starts and after
each system defrost cycle. The defrost control board com-
ponents are shown in figure 5.
The control monitors ambient temperature, outdoor coil
temperature, and total run time to determine when a de-
frost cycle is required. The coil temperature probe is de-
signed with a spring clip to allow mounting to the outside
coil tubing. The location of the coil sensor is important for
proper defrost operation.
NOTE The demand defrost board accurately measures
the performance of the system as frost accumulates on the
outdoor coil. This typically will translate into longer running
time between defrost cycles as more frost accumulates on
the outdoor coil before the board initiates defrost cycles.
