Thermistor Failure - U-Line 2224RGL User Manual & Service Manual

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.
All thermistors in the unit are identical. If a thermistor is
suspected of being defective the resistance can be
verified. Place the thermistor in an ice water bath, the
resistance should read 16.1k OHMs +/-5% on your meter.
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 dielectric grease to all of
our thermistor connections. Dielectric grease will help to
keep thermistor connections clean and dry.
If you change a thermistor in the unit please re-apply
dielectric grease to the connection. If you encounter a
dirty thermistor connection, you should replace the
thermistor and the thermistor harness.
Thermistor error information can be found in the Control
Operations - Service section.
This unit has three thermistors.
Thermistor one (Zone):
Located along the right hand side wall. It is used to
maintain the operating temperature within that zone.
Thermistor two (Evaporator):
Located on the evaporator. It is used for defrost.
Thermistor three (Ambient):
Located in the base of the unit (secured to the
condenser). It is used to monitor the ambient temperature
within the base compartment. It is used for diagnostics.

THERMISTOR FAILURE

Zone Thermistors
If a zone thermistor(s) in the unit fails the unit will
continue to cool in a backup mode (Self Preservation
Mode) to preserve the integrity of the contents. The unit
will otherwise operate normally.
2000 Series Self Preservation Mode:
The unit will cycle on for 10 minutes then off for 40
minutes.
3000 Series Self Preservation Mode:
Cycle times determined by zone - see chart. The error will
be displayed on the main display, "Self Test" and logged in
"All Errors."
Self Preservation Mode Data Table - 3000 Series
Mode
Beverage/Drinks
Market/Fresh
Root
Pantry
Deli
White Wine
Red Wine
Sparkling Wine
Polar
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. Refer to defrost section.
Ambient Thermistor
If the thermistor fails the unit will operate normally.
52
u-line.com
ON OFF
10 45
10 45
5 90
10 45
10 45
5 60
5 60
10 60
55 5
Thermistor 1