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506470-01 Issue 1007
5. Compare the subcooling value with those shown in Table
7. If subcooling is greater than shown, recover some
refrigerant. If subcooling is less than shown, add some
refrigerant.
Charge Using Approach Method (TXV System) - Outdoor
Temperatures 65°F or Above
The following procedure is intended as a general guide and
is for use on expansion valve systems only. For best results,
indoor temperature should be 70°F to 80°F. Monitor system
pressures while charging.
1. Record outdoor ambient temperature usig a digital
thermometer.
2. Attach high pressure gauge set and operate unit for
several minutes to allow system pressures to stabilize.
3. Compare stabilized pressures with those provided in Table
8. Minor variations in these pressures may be expected
due to differences in installations. Significant differences
could mean that the system is not properly charged or
that a problem exists with some component in the
system. Pressures higher than those listed indicate that
the system is overcharged. Pressures lower than those listed
indicate that the system is undercharged. Verify adjusted
charge using the approach method.
4. Use the same digital thermometer to check liquid line
temperature.
5. Subtract the outdoor ambient temperature from the liquid
line temperture to determine the approach temperature.
Page 15
Table 6
Subcooling Values
Table 5
R410A Temperature/Pressure Chart
Temp.
(F
Pressure
Psig
Temp.
(F
Pressure
Psig
Temp.
(F
Pressure
Psig
32 100.8 74 214.0 116 396.0
33 102.9 75 217.4 117 401.3
34 105.0 76 220.9 118 406.7
35 107.1 77 224.4 119 412.2
36 109.2 78 228.0 120 417.7
37 111.4 79 231.6 121 423.2
38 113.6 80 235.3 122 428.8
39 115.8 81 239.0 123 434.5
40 118.0 82 242.7 124 440.2
41 120.3 83 246.5 125 445.9
42 122.6 84 250.3 126 451.8
43 125.0 85 254.1 127 457.6
44 127.3 86 258.0 128 463.5
45 129.7 87 262.0 129 469.5
46 132.2 88 266.0 130 475.6
47 134.6 89 270.0 131 481.6
48 137.1 90 274.1 132 487.8
49 139.6 91 278.2 133 494.0
50 142.2 92 282.3 134 500.2
51 144.8 93 286.5 135 506.5
52 147.4 94 290.3 136 512.9
53 150.1 95 295.1 137 519.3
54 152.8 96 299.4 138 525.8
55 155.5 97 303.8 139 532.4
56 158.2 98 308.2 140 539.0
57 161.0 99 312.7 141 545.6
58 163.9 100 317.2 142 552.3
59 166.7 101 321.8 143 559.1
60 169.6 102 326.4 144 565.9
61 172.6 103 331.0 145 572.8
62 175.5 104 335.7 146 579.8
63 178.5 105 340.5 147 586.8
64 181.6 106 345.3 148 593.8
65 184.3 107 350.1 149 601.0
66 187.7 108 355.0 150 608.1
67 190.9 109 360.0 151 615.4
68 194.1 110 365.0 152 622.7
69 197.3 111 370.0 153 630.1
70 200.6 112 375.1 154 637.5
71 203.9 113 380.2 155 645.0
72 207.2 114 385.4
73 210.6 115 390.7
72 207.2 114 385.4
73 210.6 115 390.7