SERVICING
37
1. Attach an accurate thermometer or preferably a thermo-
couple type temperature tester to the liquid line as it leaves
the condensing unit.
2. Install a high side pressure gauge on the high side service
valve.
3. Record the gauge pressure and the temperature of the line.
4. Convert the discharge pressure gauge reading to tempera-
ture by finding the gauge reading in Temperature - Pres-
sure Chart and reading to the left, find the temperature in
the °F. Column.
5. The difference between the thermometer reading and pres-
sure to temperature conversion is the amount of subcool-
ing.
EXAMPLE:
a. Discharge Pressure = 260
b. Corresponding Temp. °F. = 120°
c. Thermometer on Liquid line = 109°F.
To obtain the amount of subcooling subtract 109°F from 120°F.
The difference is 11° subcooling. The normal subcooling range
is 10° - 15°.
DB WB
63
301 - 332
73 - 83
67 306 - 335
77 - 78
71 311 - 342
82 - 92
63 268 - 299
72 - 82
67 273 - 304
77 - 87
71 278 - 309
80 - 90
63 233 - 264
67 - 77
67 238 - 269
72 - 82
71 243 - 274
77 - 87
63 198 - 229
62 - 72
67 203 - 234
67 - 77
71 208 - 239
71 - 81
63 172 - 203
57 - 67
67 175 - 206
61 - 71
71 180 - 211
66 - 76
63 144 - 175
52 - 62
67 149 - 180
56 - 66
71 155 - 186 60 - 70
75
75
75
SUCTION
PRESSURE
PSIG
75
75
7595
85
75
65
LIQUID
PRESSURE
PSIG
INDOOR
TEMP. °F
115
105
OUTDOOR
TEMP. °F
Operating Pressures
Temp.
°F.
Gauge Pressure
(PSIG) Freon-22
Temp.
°F.
Gauge Pressure
(PSIG) Freon-22
-40
-38
-36
-34
0.61
1.42
2.27
3.15
60
62
64
65
102.5
106.3
110.2
114.2
-32
-30
-28
-26
4.07
5.02
6.01
7.03
68
70
72
74
118.3
122.5
126.8
131.2
-24
-22
-20
-18
8.09
9.18
10.31
11.48
76
78
80
82
135.7
140.5
145.0
149.5
-16
-14
-12
-10
12.61
13.94
15.24
16.59
84
86
88
90
154.7
159.8
164.9
170.1
-8
-6
-4
-2
17.99
19.44
20.94
22.49
92
94
96
96
175.4
180.9
186.5
192.1
0
2
4
6
24.09
25.73
27.44
29.21
100
102
104
106
197.9
203.8
209.9
216.0
8
10
12
14
31.04
32.93
34.88
36.89
108
110
112
114
222.3
228.7
235.2
241.9
16
18
20
22
38.96
41.09
43.28
45.53
116
118
120
122
248.7
255.6
262.6
269.7
24
26
28
30
47.85
50.24
52.70
55.23
124
126
128
130
276.9
284.1
291.4
298.8
32
34
36
38
57.83
60.51
63.27
66.11
132
134
136
136
306.3
314.0
321.9
329.9
40
42
44
46
69.02
71.99
75.04
78.18
140
142
144
146
338.0
346.3
355.0
364.3
48
50
52
54
81.40
84.70
88.10
91.5
158
150
152
154
374.1
384.3
392.3
401.3
56
58
95.1
98.8
156
158
160
411.3
421.8
433.3
TEMPERATURE-PRESSURE (R-22)
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