Service manual

The thermistor senses the refrigeration system “High side” temperature. This is used in
conjunction with the control board to determine the length of the freeze and harvest
cycles.
Thermistors generally fail due to moisture or physical damage. U-Line “high side” thermis-
tors are encased in a specially-designed, moisture-sealed aluminum block. The thermis-
tor is also mounted to the “high side” or “dry” portion of the refrigeration system. This
eliminates physical damage and moisture concerns.
Check Procedure w/LED Light on Control Board
The LED light on the control board serves three functions.
1. Steady light - The control board has power to it. There are no sensing
problems and operation is normal.
2. Slow flash - The control board has detected a sensor problem. This will
happen if the thermistor’s plug is disconnected from the
control board. This will also happen if the thermistor fails
open.
3. Rapid flashing - This indicated that the control board is receiving a high heat
signal from the thermistor. This can be caused by a dirty
condenser, inadequate air flow (unit installed behind closed
doors), failed condenser fan motor, etc.
In both the slow flash and rapid flashing situations, the unit will stop operation.
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LED Light
UL301
THERMISTOR
Service and Parts Manual
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