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14.0 FIELD INSTALLED ACCESSORIES
14.1 COMPRESSOR CRANKCASE HEATER (CCH)
While scroll compressors usually do not require crankcase heaters, there are
instances when a heater should be added. Refrigerant migration during the off cycle
can result in a noisy start up. Add a crankcase heater to minimize refrigeration
migration, and to help eliminate any start up noise or bearing “wash out.”
NOTE:
The installation of a crankcase heater is recommended if the system charge
exceeds the values in Table 6.
All heaters are located on the lower half of the compressor shell. Its purpose is to
drive refrigerant from the compressor shell during long off cycles, thus preventing
damage to the compressor during start-up.
At initial start-up or after extended shutdown periods, make sure the heater is ener-
gized for at least 12 hours before the compressor is started. (Disconnect switch on
and wall thermostat off.)
14.2 LOW AMBIENT CONTROL (LAC) – COOLING MODE ONLY
This component senses compressor head pressure and shuts the heat pump fan off
when the head pressure drops to approximately 175 PSIG. This allows the unit to
build a sufficient head pressure at lower ambient in order to maintain system bal-
ance and obtain improved capacity. Low ambient control should be used on all
equipment operated below 65°F ambient.
14.3 HIGH PRESSURE CONTROL (HPC)
This control keeps the compressor from operating in pressure ranges which can
cause damage to the compressor. This control is in the low voltage control circuit.
High pressure control (HPC) is a manual reset which opens near 450 PSIG. Do not
reset arbitrarily without first determining what caused it to trip.
15.0 SERVICE
15.1 SINGLE-POLE COMPRESSOR CONTACTOR (CC)
CAUTION
Single-pole contactors are used on all standard single-phase units up
through 5 tons. Caution must be exercised when servicing as only one leg
of the power supply is broken with the contactor.
TABLE 6
MAXIMUM SYSTEM CHARGE VALUES
Charge Limit
Model
Compressor
Without
Size*
Model Number
Crankcase Heat*
42
H23C383ABCA
8.0 lbs.
48
H23C453ABCA
8.0 lbs.
*All other models come with the crankcase heater factory-installed.
