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B-Cooling Components
cooling circuits consisting of separate compressors, con-
-
sisting of two compressors, one condenser coil, and one
and 300U unit details.
Three draw-through type condenser fans are used in
LGH156 units, four draw-through type condenser fans are
used in LGH180H units and six draw-through type con-
denser fans are used in LGH180U, LGH210, 240 and 300
units. All units are equipped with belt-drive blowers which
draw air across the evaporator during unit operation.
-
stalled economizer. The evaporators used for standard
Ultra units use an intertwined eveaporator. Each evapo-
rator uses a thermostatic expansion valve as the primary
expansion device. Each evaporator is also equipped with
-
pressor is protected by a crankcase heater, high pressure
switch and low pressure switch. Additional protection is
provided by low ambient switches and freezestats (on
each evaporator).
1-Compressors B1, B2, B13 (all units) B20 (180U, 240,
300)
All units use scroll compressors. LGH156, 180H and 210
use 3 compressors and LGH180U, 240 and 300 use four
compressors are equipped with independent cooling cir-
a common cooling circuit. Compressor capacity may vary
from stage to stage. In all cases, the capacity of each
compressor is added to reach the total capacity of the unit.
See “SPECIFICATIONS” and “ELECTRICAL DATA” (ta-
ble of contents) or compressor nameplate for compressor
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.
If Interlink compressor replacement is necessary, call
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-Crankcase Heaters HR1, HR2, HR5 (all units) HR11
(180U, 240, 300)
All LGH units use insertion type heaters. Heater HR1 is
installed around compressor B1, heater HR2 compressor
B2, HR5 compressor B13 and HR11 compressor B20.
3-High Pressure Switches S4, S7, S28, S96
S4 all units
S28 all units
The high pressure switches is an auto-reset SPST N.C.
switch which opens on a pressure rise. All units are
equipped with this switch. The switch is located in the
compressor discharge line and is wired in series with the
compressor contactor coil through A55 unit controller or
A178 compressor 3 and 4 controller (earlier units will have
are wired in series with the respective compressor con-
series with B1 and B2 compressor contactors and S28 is
wired in series with B13 and B20 compressor contactors.
When discharge pressure rises to 640 ± 10 psig (4413 ±
opens and the respective compressor(s) is de-energized
(the economizer can continue to operate). When dis-
charge pressure drops to 475 ± 20 psig (3275 ± 138 kPa)
the pressure switch will close re-energizing the compres-
sor(s).
Main control A55 has a three-strike counter before lock-
ing out. This means the control allows three high pressure
trips per one thermostat demand. The control can be reset
by breaking and remaking the thermostat demand or man-
ually resetting the control.
4-Low Ambient Switches S11, S84, S85 (all units) S94
(240, 300)
S11 all units
S85 all units
The low ambient switch is an auto-reset SPST N.O. pres-
sure switch which allows for mechanical cooling operation
at low outdoor temperatures. All units are equipped with
this switch. In all models a switch is located in each liquid
line prior to the indoor coil section.
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