Lennox LHT Series Service Manual page 20

B-Cooling Components
Units use independent cooling circuits consisting of one
compressor, one condenser coil, and one evaporator coil
per circuit.
Six draw-through type condenser fans are used in LHT156,
180 & 240.
Cooling may be supplemented by a factory- or field-in-
stalled economizer. All units intertwined evaporators.
Each evaporator uses a thermostatic expansion valve as
the primary expansion device. Each evaporator is also
equipped with enhanced fins and rifled tubing. In all units
each compressor is protected by a crankcase heater, high
pressure switch and low pressure switch.
1-Compressors B1 and B2
All units use scroll compressors. All units use 2 compres-
sors, the first stage compressor is a 2-speed and the sec-
ond stage compressor is fixed speed. Compressor capac-
ity 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" (table of contents) or compressor nameplate for
compressor specifications.
REFRIGERANT CIRCUITS
INDOOR COIL CIRCUIT 1 & 2
ARE INTERLACED
CIRUIT 2
OUTDOOR COIL
FIGURE 8
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 specific unit
operation.
If a compressor replacement is necessary, call 1-800-453-
6669.
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.
Page 20
CIRCUIT 1
OUTDOOR COIL
WARNING
IMPORTANT