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B-Cooling Components
All units use independent cooling circuits consisting of
belt-drive blowers which draw air across the evaporator
during unit operation.
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stalled economizer. The evaporators are row-split. Circuit
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tering device. Circuit #1 is located after circuit #2 on the
same evaporator slab. Circuit #1 always is equipped with
a TXV. Each evaporator is also equipped with enhanced
In all units each compressor is protected by S4 and S7
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ditional compressor protection. Each compressor is pro-
tected by a crankcase heater.
1-Compressors B1 and B2
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ever Circuit #1 B1 uses a 2-stage or 2-step compressor.
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pressor capacity may vary from stage to stage. In all cas-
WARNING
Electrical shock hazard. Compressor must be
grounded. Do not operate without protective cover
over terminals. Disconnect power before removing
protective cover. Discharge capacitors before
servicing unit. Failure to follow these precautions
could cause electrical shock resulting in injury or
death.
Each compressor is energized by a corresponding com-
pressor contactor.
NOTE-Refer to the wiring diagram section for specic unit
operation.
IMPORTANT
Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction
pressure goes below 20 psig. A hissing sound
will be heard when the compressor is running
unloaded. Protector will reset when low pressure
in system rises above 40 psig. DO NOT REPLACE
COMPRESSOR.
2-High Pressure Switches S4 and S7
The high pressure switch is an auto-reset SPST N.C.
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charge line and wired in series with the respective com-
pressor contactor coils.
opens and the respective compressor is de-energized
the S4 high pressure switch located in the liquid line be-
3-Low Ambient Switches S11 & S84 (optional)
The low ambient switch is an auto-reset SPST N.O. pres-
sure switch which allows for mechanical cooling operation
at low outdoor temperatures. In all models a switch is lo-
cated in each liquid line prior to the indoor coil section.
outdoor fan relay K10.
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ergized. When liquid pressure in both refrigerant circuits
and the condenser fans are de-energized. This intermit-
tent fan operation results in higher evaporating tempera-
ture allowing the system to operate without icing the evap-
orator coil and losing capacity.
4-Crankcase Heaters HR1, HR2
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around compressor B2. Crankcase heater wattage varies
by compressor manufacturer. The power to crankcase
heaters is routed through the N.C. Contacts on K10 Out-
C-Blower Compartment
All units are equipped with belt drive blowers.
1-Blower Wheels
2-Indoor Blower Motor B3
All units use three-phase single-speed blower motors.
equipped with motors manufactured by various manufac-
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ate the blower depending on which thermostat signals in
= 60Hz.
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