Page 21
LGM/LCM036, 048, 060, 074
TABLE 6 581010-01
LG/LC 048U NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air Temp
Discharge
+10 psig
S 5
psig
65
5
F
252
142
75
5
F
289
145
85
5
F
332
147
95
5
F
379
149
105
5
F
428
151
115
5
F
484
153
TABLE 7 581011-01
LG/LC 060U NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air Temp
Discharge
+10 psig
S 5
psig
65
5
F
261
135
75
5
F
299
138
85
5
F
341
140
95
5
F
388
142
105
5
F
441
144
115
5
F
499
146
TABLE 8 581012-01
LG/LC 074U NORMAL OPERATING PRESSURES
Outdoor Coil
Entering Air Temp
Discharge
+10 psig
S 5
psig
65
5
F
268
128
75
5
F
307
134
85
5
F
351
137
95
5
F
399
140
105
5
F
450
142
115
5
F
505
144
TABLE 9
SUBCOOLING TEMPERATURE
Unit
Liquid Saturated Temp. Minus
Liquid Temperature
036U
11°F + 1 (6.0°C + 0.5)
048U
11.5°F + 1 (6.4°C + 0.5)
060U
13.5°F + 1 (7.5°C + 0.5)
074U
15°F + 1 (8.3°C + 0.5)
C-Compressor Controls
See unit wiring diagram to determine which controls are
used on each unit. Optional controls are identified on
wiring diagrams by arrows at junction points.
1- High Pressure Switch (S4)
The compressor circuit is protected by a high
pressure switch which opens at 640 psig + 10 psig
(4413 kPa + 70 kPa) and automatically resets at 475
psig + 20 psig (3 138 kPa).
2- Low Pressure Switch (S87)
The compressor circuit is protected by a loss of
charge switch. Switch opens at 40 psig + 5 psig (276
+ 34 kPa) and automatically resets at 90 psig + 5
psig (621 kPa + 34 kPa).
3- Prognostics and Diagnostics Sensors (RT42, RT44,
RT46, RT48)
Four thermistors are located on specific points in the
refrigeration circuit. The thermistors provide constant
temperature feedback to the Unit Controller to protect
the compressor. Thermistors take the place of the
freezestat and low ambient pressure switch.
4- Compressor Crankcase Heater (HR1)
Crankcase heater must be energized at all times to
prevent compressor damage due to refrigerant
migration. Energize crankcase heater 24 hours before
unit start-up by setting thermostat so that there is no
cooling demand (to prevent compressor from cycling)
and apply power to unit.
