Carrier 19DV Series - Resistance Check; Voltage Drop Check

109
temperature by measuring voltage drop; if the controls are powered off, determine sensor temperature by
measuring resistance. Compare the readings to the values listed in Table 22.
10.4 Resistance Check
Turn off the control power from the module, disconnect the terminal plug of the sensor in question. With a digital
ohmmeter, measure sensor resistance between receptacles as designated by the wiring diagram. The resistance
and corresponding temperature are listed in table 22. Check the resistance of both wires to ground .This
resistance should be infinite.
10.5 Voltage Drop Check
The voltage drop across any energized sensor can be measured with a digital voltmeter while the control is
energized. Table 22 lists the relationship between temperature and sensor voltage drop (dv volts measured
across the energized sensor). Exercise care when measuring voltage to prevent damage to the sensor leads,
connector plugs, and modules. Sensors should also be checked at the sensor plugs.
CAUTION: Relieve all refrigerant pressure or drain the water before removing any thermowell threaded into the
refrigerant pressure boundary. Failure to do so could result in personal injury and equipment damage.
Temperature
(°C)
Pic
voltage
drop (V)
Resistance
(Ohms)
T
(°C)
Pic v.d.
(V)
R
(Ohms)
T
(°C)
Pic
v.d.
(V)
R
(Ohms)
T
(°C)
Pic v.d.
(V)
R
(Ohms)
-33
4.722
105 616
7
3.242
11 510
47
1.227
2 021
87
0.376
502
-32
4.706
99 640
8
3.185
10 963
48
1.192
1 944
88
0.365
487
-31
4.688
93 928
9
3.129
10 444
49
1.158
1 871
89
0.355
472
-30
4.67
88 480
10
3.074
9 949
50
1.124
1 801
90
0.344
458
-29
4.65
83 297
11
3.016
9 486
51
1.091
1 734
91
0.335
444
-28
4.63
78 377
12
2.959
9 046
52
1.06
1 670
92
0.325
431
-27
4.608
73 722
13
2.901
8 628
53
1.029
1 609
93
0.316
418
-26
4.586
69 332
14
2.844
8 232
54
0.999
1 550
94
0.308
405
-25
4.562
65 205
15
2.788
7 855
55
0.969
1 493
95
0.299
393
-24
4.538
61 343
16
2.73
7 499
56
0.941
1 439
96
0.291
382
-23
4.512
57 745
17
2.672
7 160
57
0.913
1 387
97
0.283
371
-22
4.486
54 411
18
2.615
6 839
58
0.887
1 337
98
0.275
360
-21
4.458
51 341
19
2.559
6 535
59
0.861
1 290
99
0.267
349
-20
4.429
48 536
20
2.503
6 246
60
0.835
1 244
100
0.26
339
-19
4.399
45 819
21
2.447
5 972
61
0.811
1 200
101
0.253
330
-18
4.368
43 263
22
2.391
5 711
62
0.787
1 158
102
0.246
320
-17
4.336
40 858
23
2.335
5 463
63
0.764
1 117
103
0.239
311
-16
4.303
38 598
24
2.28
5 226
64
0.741
1 079
104
0.233
302
-15
4.269
36 476
25
2.227
5 000
65
0.719
1 041
105
0.227
294
-14
4.233
34 484
26
2.173
4 787
66
0.698
1 006
106
0.221
286
-13
4.196
32 613
27
2.12
4 583
67
0.677
971
107
0.215
278
-12
4.158
30 858
28
2.067
4 389
68
0.657
938
108
0.21
270
-11
4.119
29 211
29
2.015
4 204
69
0.638
906
109
0.205
262
-10
4.079
27 663
30
1.965
4 028
70
0.619
876
110
0.198
255
-9
4.037
26 208
31
1.914
3 861
71
0.601
846
111
0.193
248
-8
3.994
24 838
32
1.865
3 701
72
0.583
818
112
0.188
242
-7
3.951
23 545
33
1.816
3 549
73
0.566
791
113
0.183
235
-6
3.906
22 323
34
1.768
3 404
74
0.549
765
114
0.178
229
-5
3.861
21 163
35
1.721
3 266
75
0.533
740
115
0.174
223
-4
3.814
20 083
36
1.675
3 134
76
0.518
715
116
0.17
217
-3
3.765
19 062
37
1.629
3 008
77
0.503
692
117
0.165
211
-2
3.716
18 097
38
1.585
2 888
78
0.488
670
118
0.161
205
-1
3.667
17 185
39
1.542
2 773
79
0.474
648
119
0.157
200
0
3.617
16 325
40
1.499
2 663
80
0.46
628
120
0.153
195
1
3.565
15 513
41
1.457
2 559
81
0.447
608
2
3.512
14 747
42
1.417
2 459
82
0.434
588
3
3.459
14 023
43
1.377
2 363
83
0.422
570
4
3.406
13 341
44
1.338
2 272
84
0.41
552
5
3.353
12 696
45
1.3
2 184
85
0.398
535
6
3.298
12 087
46
1.263
2 101
86
0.387
518
Table 22 – Voltage drop and resistance vs temperature