Manitowoc STH042 4/16, Technician'S Handbook

Page: 106 / 146

106 Part Number STH042 4/16
Water Trough Thermistor
Function
Thermistor resistance values change with temperature.
The value supplied to the control board is used to identify
temperature at the thermistor location.
When the resistance value indicates a temperature of
34°F (1.1°C) the control board will delay the water pump
for 25 seconds. When the water pump restarts the water
inlet valve will energize for 7 seconds then turn off.
Check procedure
THERMISTOR
1. Disconnect thermistor from control board and
measure resistance.
2. Measure temperature at the thermistor.
3. Compare measured resistance/temperature readings
to resistance/temperature relationship chart.
A. Within 10% of the published resistance value
Thermistor is good
B. Not within 10% of the published resistance
value - Thermistor is defective.
CONTROL BOARD OPERATION
1. Disconnect thermistor from control board - The
control board thermistor LED will flash 1 second on
and 1 second off.
2. The control board will default to the 3.75 minute
pump delay in the freeze cycle.