Page 47
LGH/LCH036, 048, 060, 072, 074
If pressure differential is not observed or blower rotation is
not correct:
3- Disconnect all remote electrical power supplies.
4- Reverse any two field-installed wires connected to
the line side of K1 contactor. Do not reverse wires at
blower contactor.
5- Make sure the connections are tight.
Discharge and suction pressures should operate at
their normal start‐up ranges.
C-Refrigerant Charge and Check - All-Aluminum Coil
WARNING-Do not exceed nameplate charge under
any condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant,
reclaim the charge,
evacuate the system, and add
required nameplate charge.
NOTE - System charging is not recommended below
60F (15C). In temperatures below 60F (15C), the
charge must be weighed into the system.
If weighing facilities are not available, or to check the
charge, use the following procedure:
IMPORTANT - Charge unit in standard cooling mode
high stage only
.
1- Make sure outdoor coil is clean. Attach gauge
manifolds and operate unit at full CFM in cooling mode
with economizer disabled until system stabilizes
(approximately five minutes). Make sure all outdoor air
dampers are closed.
2- Compare the normal operating pressures (see tables
10 - 18) to the pressures obtained from the gauges.
Check unit components if there are significant
differences.
3- Measure the outdoor ambient temperature and the
suction pressure. Refer to the appropriate circuit
charging curve to determine a target liquid
temperature.
Note - Pressures are listed for sea level applications.
4- Use the same thermometer to accurately measure the
liquid temperature (in the outdoor section).
If measured liquid temperature is higher than
the target liquid temperature, add refrigerant to
the system.
If measured liquid temperature is lower than
the target liquid temperature, recover some
refrigerant from the system.
5- Add or remove charge in increments. Allow the
system to stabilize each time refrigerant is added or
removed.
6- Continue the process until measured liquid
temperature agrees with the target liquid
temperature. Do not go below the target liquid
temperature when adjusting charge. Note that
suction pressure can change as charge is adjusted.
7- Example LGH/LCH036H: At 95°F outdoor ambient
and a measured suction pressure of 130psig, the
target liquid temperature is 98°F. For a measured
liquid temperature of 106°F, add charge in
increments until measured liquid temperature agrees
with the target liquid temperature.
TABLE 10
LGH/LCH036S/H NORMAL OPERATING PRESSURES - ALL-ALUMINUM COIL
Outdoor Coil Entering Air Temperature
65 °F 75 °F 85 °F 95 °F 105 °F 115 °F
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
Suct
(psig)
Disc
(psig)
114 239 117 279 118 329 119 381 122 441 124 516
121 242 123 284 126 328 128 379 129 442 132 517
138 252 142 291 145 335 148 382 151 434 152 506
156 266 160 301 164 344 168 393 172 446 175 503
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