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C−Blower Compartment
The blower compartment in all SCA120 units is located be-
tween the evaporator coil and the condenser coil section.
The blower assembly is accessed by removing the screws
in front of the blower housing. The blower pulls out as
shown in figure 12.
The blower compartment in SCA240/SCB288 units is lo-
cated between the evaporator coil and the compressor / con-
trol section on the opposite side of the condenser coil. The
blower assembly is accessed by removing the screws on ei-
ther side of the sliding base. The blower pulls out as shown in
figure 13.
1−Blower Wheels
SCA120 units have one 15 in. x 15 in. (381 mm x 381 mm)
blower wheel.
SCA240/SCB288 units have two 18 in. x 15 in. (457 mm x 381
mm) blower wheels. Both wheels are driven by one motor.
2−Indoor Blower Motor B3
All units use three-phase single-speed blower motors.
CFM adjustments for the CAV units are made by adjusting
the motor pulley (sheave). Motors are equipped with
sealed ball bearings. All motor specifications are listed in
the SPECIFICATIONS (table of contents) in the front of this
manual. Units may be equipped with motors manufactured
by various manufacturers, therefore electrical FLA and
LRA specifications will vary. See unit rating plate for infor-
mation specific to your unit.
OPERATION / ADJUSTMENT
IMPORTANT
Three phase scroll compressors must be phased se-
quentially for correct compressor and blower rota-
tion. Follow COOLING START−UP" section to en-
sure proper compressor and blower operation.
A−Blower Operation
Initiate blower demand at thermostat according to instruc-
tions provided with thermostat. Unit will cycle on thermostat
demand. The following steps apply to applications using a
typical thermostat. MSAV units refer to the Optional Supply
Air VFD section.
1− Blower operation is manually set at the thermostat sub-
base fan switch. With fan switch in ON position, blow-
ers will operate continuously.
2− With fan switch in AUTO position, the blowers will cycle
with demand. Blowers and entire unit will be off when
system switch is in OFF position.
B−Blower Access
1− Disconnect wiring to heating limit switches and mixed
air sensor (units with economizer).
2− Remove screws on either side of blower assembly slid-
ing base. See figure 12 (SCA120) or 13
(SCA240SCB288).
3− Pull base toward outside of unit.
C−Determining Unit CFM
1− Measure the indoor blower motor RPM. Air filters must
be in place when measurements are taken.
2− With all access panels in place, measure static pres-
sure external to unit (from supply to return).
3− Referring to tables in BLOWER DATA (table of con-
tents) use static pressure and RPM readings to deter-
mine unit CFM.
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