3DJH
TABLE 4
NORMAL OPERATING PRESSURES IN PSIG (LIQUID AND S/-- 10 PSIG)*
MODE
OUT. COIL
ENTERING
10ACB12
10ACB18
10ACB24
10ACB30
10ACB36
10ACB42
10ACB48
10ACB60
10ACB62
MODE
ENTERING
AIR TEMP.
qF (qC)
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
LIQ.
SUC.
65 (18.3)
145
71
155
65
160
65
168
63
176
62
162
68
157
69
153
66
159
64
75 (23.9)
167
77
181
70
188
70
197
68
203
66
185
72
182
72
180
71
188
68
RFCIV
85 (29.4)
192
81
208
75
216
74
227
73
233
70
210
73
204
73
210
74
219
72
95 (35.0)
221
84
238
80
247
78
258
77
266
74
252
76
244
76
245
77
253
75
105 (40.6)
253
87
270
84
280
82
292
80
299
77
287
79
278
79
279
79
287
76
65 (18.3)
140
79
159
73
164
71
173
71
179
68
157
71
158
70
142
73
151
69
75 (23.9)
161
80
183
75
189
73
199
73
205
70
187
73
182
72
168
75
179
71
TXV
85 (29.4)
189
81
209
77
217
75
228
75
235
72
217
74
205
73
202
76
211
73
95 (35.0)
220
83
238
80
247
78
258
77
266
74
255
76
246
76
245
77
249
74
105 (40.6)
254
84
269
82
279
80
292
79
299
77
289
77
280
79
280
78
286
75
*These are typical pressures only. Indoor evaporator match up, indoor air quality and evaporator load will cause the pressures to vary.
IMPORTANT
Use table 4 as a general guide for performing main-
tenance checks. Table 4 is not a procedure for
charging the system. Minor variations in these
pressures may be expected due to differences in
installations. Significant deviations could mean
that the system is not properly charged or that a
problem exists with some component in the sys-
tem. Used prudently, table 4 could serve as a useful
service guide.
Before charging the unit, follow the procedure below
to determine: the liquid line temperature and the out-
door ambient temperature.
1 -- Connect manifold gauge set to service valves: low
pressure gauge to suction valve service port; high
pressure gauge to liquid valve service port. Con-
nect the center manifold hose to an upright bottle
of HCFC-22. Close manifold gauge set valves.
2 -- Set the room thermostat to call for heat. This will
create the necessary load for properly charging the
system in the cooling cycle.
3 -- Record the outdoor ambient temperature. For
greater accuracy, use the same electronic ther-
mometer to measure liquid temperature.
4 -- When thermostat demand has been satisfied,
switch to cooling mode with a set point of 68EF
(20EC). When pressures have stabilized, record the
liquid line temperature.
5 -- The outdoor temperature will determine which
charging method to use. Proceed with the ap-
propriate charging procedure below.
&+$5*,1* )25 5)& 6<67(06
Weighing in the Charge Method
RFC Systems, < 65EF
(18EC)
Outdoor Temp
1-- Recover the refrigerant from the unit.
2-- Conduct a leak check, then evacuate as previously
outlined.
3-- Weigh in the factory charge as shown on the out-
door units rating plate.
The Subcooling Method
RFC Systems, > 65EF
(18EC)
Outdoor Temp
1-- With the manifold gauge hose still on the liquid ser-
vice port and the unit operating stably, record the
liquid line temperature.
2-- At the same time, record the liquid line pressure
reading.
3-- Using a temperature/pressure chart for HCFC-22,
determine the saturation temperature for the liquid
line pressure reading.
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