Specifications

Page 13
WARNING
Do not exceed nameplate charge under any con
ditions. Compressor damage will result.
1- This method uses a thermometer inserted in the ther
mometer wells to check liquid line temperature. Make
sure thermometer wells are filled with oil before check
ing.
2- Operate unit (all compressors) for at least five minutes
until pressures stabilize.
3- Check each stage separately with all stages operating.
Compare liquid temperatures to outdoor ambient tem
perature. Liquid line temperature should be a few de
grees warmer than the outdoor air temperature. See
table 1. For best results use the same thermometer for
both readings.
CHA/GCS24-1603
TABLE 1
APPROACH TEMPERATURE
UNIT
LIQUID TEMP. MINUS AMBIENT TEMP.
CHA/GCS24-1353
6F + 1 (3C + 0.5)
9F + 1 (5C + 0.5)
8F + 1 (4C + 0.5)
12F + 1 (7C + 0.5)
STAGE 1 STAGE 2
Add refrigerant to make the liquid line cooler.
Recover refrigerant to make the liquid line warmer.
4- When unit is properly charged, the system pressure
should approximate pressure given in the Normal Oper
ating Pressure Table (table 2).
NOTE - Use table 2 as a general guide for performing
maintenance checks. When unit is properly charged line
pressures should approximate those given in table 2.
Table 2 is not a procedure for charging the system. Varia
tions in these pressures may be expected due to differ
ences in installations or conditions such as indoor air vol
ume, humidity and load. Significant deviations could mean
that the system is not properly charged or that a problem
exists with some component in the system. Used prudent
ly, table 2 could serve as a useful service guide.
Liq. Suct.
+ 10 + 5+ 10 + 5
PSIG PSIG PSIG PSIG
Outdoor
Entering
Air
Temp.
Stage 1 Stage 2
Liq. Suct.
GCS24 NORMAL OPERATING PRESSURES
Unit
65°F
85°F
95°F
105°F
75°F
65°F
85°F
95°F
105°F
75°F
TABLE 2
GCS24-1353
GCS24-1603
155 70
180
206
242
270
154
180
210
242
277
72
73
74
75
67
70
72
74
76
165
190
217
248
287
170
200
231
264
300
70
70
71
72
75
69
71
73
75
77
VII-INDOOR BLOWER
OPERATION / ADJUSTMENT
A-Blower Operation
NOTE-The following is a generalized procedure and does
not apply to all thermostat control systems.
1- Blower operation is dependent on the thermostat control
system option that has been installed in the GCS24. Re
fer to the operation sequence for the control system
installed for detailed descriptions of blower operation.
2- Generally, blower operation is set at the thermostat fan
switch. With the fan switch in ON" position, the blower
operates continuously. With the fan switch in AUTO"
position, the blower cycles with demand (or, with some
control systems, runs continuously while the heating or
cooling circuits cycle).
3- In most cases, the blower and entire unit will be off when
the system switch is in the OFF" position. The only ex
ception is immediately after a heating demand until blow
er control switches off.
B-Determining Unit CFM
1- The following measurements must be made with a dry in
door coil. Run blower without a cooling demand. Air filters
must be in place when measurements are taken.
2- With all access panels in place, measure static pressure
external to unit (from supply to return).
3- Measure the indoor blower motor RPM.
4- Referring to tables 3 and 4 , use static pressure and RPM
readings to determine unit CFM.
5- The CFM can be adjusted at the motor pulley. Loosen Al
len screw and turn adjustable pulley clockwise to in
crease CFM. Turn counterclockwise to decrease CFM.
See figure 10.