TM 9-4120-385-14
4. Connect the power supply and turn the mode selector switch to COOL and
temperature selector switch to maximum INCREASE.
5. Slowly open the low pressure service valve. Operate the unit for 30 minutes to
allow the system and the thermometer to stabilize.
6. Observe the low pressure (suction) guage. Record the gauge reading and add
2 psig for estimated line loss.
7. Refer to Table 5-9 and convert pressure recorded in Step 6 (including 2 psig
additional for line loss) to temperature.
Tempera-
Tempera-
Tempera-
Tempera-
Pressure
Pressure
Pressure
Pressure
k g / c m2
k g / c m2
ture C
ture C
ture F
ture F
PSIG
PSIG
17.77
24.0
48.8
1.68
3.43
25
3.88
0
17.22
24.8
1
1.74
26
-3.33
49.9
3.50
2.77
2
1.80
16.66
27
25.6
51.2
3.60
16.10
26.4
2.22
3.68
1.86
28
52.4
3
1.66
4
1.92
15.55
27.3
29
53.6
3.77
1.11
3.86
1.98
15.00
28.2
54.9
5
30
14.44
29.1
3.95
6
2.05
31
-0.55
56.2
4.04
13.88
2.11
30.0
32
0.00
57.5
7
4.13
13.33
0.55
2.17
30.9
33
58.8
8
4.22
12.77
1.11
2.23
31.8
60.1
9
34
1.66
4.31
2.31
12.22
61.5
10
32.8
35
4.42
2.22
2.37
11.66
33.7
62.8
11
36
2.77
4.51
11.11
64.2
12
2.44
34.7
37
4.61
2.51
10.55
65.6
3.33
13
35.7
38
4.72
2.58
10.00
67.1
3.88
14
36.7
39
4.82
68.5
4.44
15
2.65
9.44
37.7
40
4.92
70.0
5.00
2.72
-8.88
38.7
41
16
5.02
2.80
71.4
42
5.55
17
-8.33
39.8
5.13
73.0
6.11
18
2.67
-7.77
40.8
43
5.24
74.5
6.66
2.95
7.22
41.9
44
19
5.34
76.0
7.22
3.02
-6.66
43.0
45
20
5.46
77.6
44.1
46
7.77
3.10
-6.11
21
5.57
79.2
8.33
3.19
45.3
47
22
5.55
5.68
80.8
48
8.88
46.4
23
3.26
-5.00
4.44
47.6
24
3.35
8. Observe and record the temperature indicated on the thermometer. Deduct the
temperature calculated in Step 7 from this reading to obtain superheat. Superheat of the
expansion valve should be 6 F +/ 1/2 F hotter than the temperature calculated in Table 5-9.
The expansion valve should not be adjusted if superheat is not specified.