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12HPB24
Outdoor Coil
Outdoor Coil
Air Entering
liq.
Temp.
+10
_F (_C)
PSIG
65 (183.)
144
75 (23.9)
170
85 (29.4)
199
95 (35)
228
105 (40.6)
261
NOTE − Typical pressures only. Indoor evaporator match up, indoor air quantity, and evaporator load will cause the pressures to vary.
SUBCOOLING METHOD (TXV SYSTEMS)
(Ambient Temperature Below 60_F [16_C]
NOTE- It may be necessary to restrict air flow in order to
reach liquid pressures in the 200-250 psig range which
are required for checking charge. The indoor temperature
should be above 70_F (21_C). Block equal sections of air
intake panels, moving obstructions sideways until liquid
pressures in the 200-250 psig range are reached.
1 − Connect gauge manifold. Connect an upright R−22
drum to center port of gauge manifold.
2 − Operate indoor and outdoor units in cooling mode.
Allow outdoor unit to run until system pressures sta-
bilize.
3 − Make sure thermometer well is filled with mineral oil
before checking liquid line temperature.
4 − Read liquid line pressure and convert to con-
densing temperature using temperature/pres-
sure conversion chart.
Condensing temperature (read from gauges)
should be warmer than the liquid line tempera-
ture.
5 − Place thermometer in well and read liquid line tem-
perature. Table 8 shows how much warmer the con-
densing temperature should be.
Add refrigerant to lower liquid line temperature.
Recover refrigerant to raise the liquid line tem-
perature.
6 − When unit is properly charged liquid line pres-
sures should approximate those given in table
7.
TABLE 8
SUBCOOLING METHOD
AMBIENT TEMPERATURE BELOW 60 _F (16 _C)
Model
Condensing Temp°F Warmer Than Liquid Line
12HPB24
12HPB30
12HPB36
12HPB42
12HPB48
12HPB60
12HPB30
vap.
liq.
vap.
+5
+10
+5
PSIG
PSIG
PSIG
78
140
76
79
164
77
80
194
78
81
224
79
82
259
80
11°F (6.1°C)
5°F (2.8°C)
3°F (1.7°C)
4°F (2.2°C)
4°F (2.2°C)
6°F (3.3°C)
TABLE 7
12HPB36
12HPB42
liq.
vap.
liq.
+10
+5
+10
PSIG
PSIG
PSIG
152
74
152
178
76
179
208
77
210
238
78
241
275
81
278
Use table 7 as a general guide for performing mainte-
nance checks. Table 7 is not a procedure for charg-
ing 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 system. Used prudently,
table 7 could serve as a useful service guide.
E − Oil Charge
See compressor nameplate.
IV − MAINTENANCE
At the beginning of each heating or cooling season, the
system should be cleaned as follows:
A − Outdoor Unit
1 − Clean and inspect condenser coil. (Coil may be
flushed with a water hose).
NOTE − Make sure all power is disconnected before
flushing coil with water.
2 − Visually inspect all connecting lines, joints and
coils for evidence of oil leaks.
NOTE-Outdoor fan motors are permanently
lubricated.
B − Indoor Coil
1 − Clean coil if necessary.
2 − Check connecting lines and coil for evidence of oil
leaks.
3 − Check condensate line and clean if necessary.
C − Indoor Unit
1 − Clean or change filters.
2 − Bearings are pre-lubricated and need no further oil-
ing.
3 − Check all wiring for loose connections.
4 − Check for correct voltage at unit.
5 − Check amp−draw on blower motor.
Page 13
12HPB48
vap.
liq.
vap.
+5
+10
+5
PSIG
PSIG
PSIG
75
146
75
76
171
77
77
198
78
78
229
79
79
268
81
IMPORTANT
12HPB60
liq.
vap.
+10
+5
PSIG
PSIG
146
73
175
74
206
75
237
76
275
77
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