U-Line 2260ZWC User Manual page 63

USER GUIDE
SAFETY • INSTALLATION & INTEGRATION • OPERATING INSTRUCTIONS • MAINTENANCE • SERVICE
Thermistors
Thermistors are used for various temperature readings.
Thermistors provide reliable temperature readings using a
resistance which varies based on surrounding
temperatures. If a faulty thermistor is suspected it may
be tested using an accurate ohmmeter.
THERMISTOR FAILURE
Zone Thermistors
If a zone thermistor in the unit fails the unit will continue
to cool in a back up mode to preserve the integrity of the
contents. The unit will cycle on for ten minutes, then shut
down for forty five minutes. The process will repeat until
the problem is corrected. All other functions of the unit
will continue to operate normally.
Evaporator Thermistors
If an evaporator thermistor fails the unit will rely on a
preset defrost timer during defrost cycles. The unit will
otherwise operate normally. Evaporator thermistor errors
are recorded in service mode "Error Log" section.
This unit has four thermistors. Thermistor one is located
along the right hand side wall. It is used to maintain the
operating temperature within that zone.
Thermistor two is located on the back of the evaporator in
the top zone and is used for defrost purposes.
Thermistor three is located along the right hand side wall
in the bottom zone. It is used to maintain the operating
temperature within that zone.
Thermistor four is located on the back of the evaporator in
the bottom zone and is used for defrost purposes.
All four of the thermistors in the unit are identical. If a
thermistor is suspected of being defective it can be
OHMed out. In an ice water bath the thermistor should
OHM out at 16.1k OHMS +/-5%.
Thermistor connections must be kept clean. A thermistor
connection that has become corroded can cause
resistance values from the thermistor to change as they
pass through a dirty connection to the board.
It is for that reason that we apply die electric grease to all
of our thermistor connections. Die electric grease will help
to keep thermistor connections clean and dry.
If you change a thermistor in the unit please re-apply die
electric grease to the connection. If you encounter a dirty
thermistor connection, you should replace the thermistor
and the thermistor harness.
Thermistor Resistance Data
Temp (F) Temp (C)
-40 -40
-31 -35
-22 -30
-13 -25
-4 -20
5 -15
14 -10
23 -5
32 0
41 5
50 10
59 15
68 20
77 25
86 30
95 35
104 40
113 45
122 50
131 55
140 60
149 65
158 70
167 75
176 80
* (=/-5%)
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Nominal Resistance
(OHMS)*
169157
121795
88766
65333
48614
36503
27681
21166
16330
12696
9951
7855
6246
5000
4029
3266
2665
2186
1803
1495
1247
1044
879
743
631
Thermistor 1