7
Thermistor Field Testing
Use the guide below to test if a thermistor (temperature probe) is functioning properly. See the replacement parts list for
part number information. Table 2 is valid for all thermistors listed on table 1.
Establish Thermistor Temperature
Check the display’s temperature reading.
If a thermometer is available, use it to confirm the display’s
temperature reading by taking the temperature at the
thermistor.
If the previously stated tasks are unavailable, then use any
reasonable means to estimate the thermistors temperature.
See form M164 for ice bath method. (ice water is 32
°
F)
Multimeter Set-up
Use a multimeter and set it to the resistance (Ω) setting. See
Figure 1.
Disconnect the thermistor from the controller, then connect the
multimeter to the thermistor. See Figure 1.
Check and compare the multimeter’s reading to Table 1.
Analyze Results
If the resistance and temperature are similar, then the
thermistor is working properly and does not need to be
replaced.
If the resistance and temperature are not similar or the
resistance’s value is not on Table 1, then the thermistor is not
working properly and needs to be replaced.
If the resistance reads over-limit, then the thermistor is not
working properly and needs to be replaced.
Figure 1
Table 1
Thermistor Description
Part Number
60” black
120” black
60” green
120” green
96” black
Table 2
Temp
(
°
F)
Ohms
(kΩ)
Temp
(
°
C)
-4.0
67.8
-20
-0.4
61.5
-18
3.2
56.0
-16
6.8
51.0
-14
10.4
46.5
-12
14.0
42.5
-10
17.6
38.8
-8
21.2
35.4
-6
24.8
32.4
-4
28.4
29.7
-2
32.0
27.3
0
35.6
25.0
2
39.2
23.0
4
42.8
21.2
6
46.4
19.5
8
50.0
18.0
10
53.6
16.6
12
57.2
15.3
14
60.8
14.1
16
64.4
13.0
18
68.0
12.1
20
71.6
11.2
22
75.2
10.4
24
78.8
9.6
26
82.4
8.9
28
86.0
8.3
30
89.6
7.7
32
93.2
7.2
34
96.8
6.7
36
100.4
6.3
38
104
5.8
40
P/N 45810 - Rev C
