Troubleshooting - Procedure E; Verifying Thermistor Operation - Norcold DC0040 Service Manual

Troubleshooting - Procedure E

Verifying Thermistor Operation

To measure the resistance of the evaporator thermistor, com-
plete the following procedure.
1. Turn the temperature control to the "Off" position.
2. Disconnect the 3-pole connector. Refer to Figure 7.
3. Measure the resistance across the two pins. Refer to
Figure 8.
4. Check the evaporator thermistor by measuring the tem-
perature and resistance of the thermistor.
Refer to Table 1 for a listing of acceptable resistance
ranges.
NOTE: In general, 1.6K - 29KΩ = good thermistor.
∞Ω = defective thermistor. An open thermistor
will stop normal compressor operation. Replace
the defective thermistor.
Figure 7. Evaporator Thermistor Connection
(Inside Power Supply)
Thermistor Temperature
Refrigerator Service Manual
Evaporator Thermistor Resistance
(°F) (°C)
0 -18
10 -12
20 -7
30 -1
40 4
50 10
60 16
70 21
80 27
90 32
Table 1. Evaporator Thermistor Resistance
DC0040(K), DC0051(K), DE0040, DE0051, DE0240T, DE0251T,
DC0740(X), DE0740(X), DC0751(X), DE0751(X) Models
Figure 8. Measure Resistance Across Pins
Resistance Allowable
Resistance
Range
9.7 KΩ 8.7 - 10.7 KΩ
7.8 KΩ 7.0 - 8.6 KΩ
6.4 KΩ 5.7 - 7.0 KΩ
5.3 KΩ 4.8 - 5.7 KΩ
4.5 KΩ 4.0 - 4.9 KΩ
3.6 KΩ 3.2 - 4.0 KΩ
2.8 KΩ 2.5 - 3.1 KΩ
2.1 KΩ 1.9 - 2.3 KΩ
1.9 KΩ 1.7 - 2.0 KΩ
1.8 KΩ 1.6 - 1.9 KΩ
7