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5−Freezestats S49 and S50 (all units)
S53 & S95(SCA240/SCB288)
Each unit is equipped with a low temperature switch (free-
zestat) located on the return bend of each evaporator coil.
S49 (first circuit), S50 (second circuit), S53 (third circuit),
and S95 (fourth circuit) are located on the corresponding
evaporator coils.
Each freezestat is wired to the main control module A55.
Each freezestat is a SPST N.C. auto−reset switch which
opens at 29F + 3F (-1.7C + 1.7C) on a temperature drop
and closes at 58F + 4F (14.4C + 2.2C) on a temperature
rise. To prevent coil icing, freezestats open during com-
pressor operation to temporarily disable the respective
compressor until the coil warms sufficiently to melt any ac-
cumulated frost.
If the freezestats are tripping frequently due to coil icing,
check the unit charge, airflow and filters before allowing
unit back in operation. Make sure to eliminate conditions
which might promote evaporator ice buildup.
6−Condenser Fans B4 & B5 (all units)
B21, B22, B23 & B24 (SCA240SCB288)
See SPECIFICATIONS" tables at the front of this manual
for the specifications of condenser fans used in all units. All
condenser fans used have single−phase motors. The com-
plete fan assembly may be removed for servicing and
cleaning by removing the fan grill and turning the complete
assembly until the motor brackets line up with the notches
in the top panel. Lift the fan assembly out of the unit and dis-
connect the jack plug located on the motor.
7−Crankcase Heaters HR1 & HR2 −
Thermostats S40 & S162
Each compressor is protected by a crankcase heater and
thermostat. The purpose of the crankcase heater is to pre-
vent liquid from accumulating in the compressor. In the
SCA120Crankcase heater HR1 and thermostat S40 pro-
tects compressor B1 while crankcase heater HR2 and ther-
mostat S162 protects compressor B2. In the
SCA240/SCB288 HR1, HR2 and S40 protects compres-
sors B1 and B2 while HR5, HR11and S162 protects com-
pressors B13 and B20. See unit diagram. The crankcase
heater and compressor never run at the same time.
The thermostats S40 and S162 are located in the compres-
sor discharge line and will open once discharge line tem-
perature reaches 94°, de−energizing the compressors
crankcase heater. Once temperature drops down to 74°
the thermostats close energizing the crankcase heater.
8−Filter Drier (all units)
SCA/SCB units have a filter drier located in the liquid line of
each refrigerant circuit at the exit of each condenser coil.
The drier removes contaminants and moisture from the
system.
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