[D] Control Board Check Procedure - Hoshizaki KM-40B Service Manual

k) Overfreeze Detection Control (S2 dip switch 5)
Do not adjust. This must be left in the factory default position or the unit will not operate
properly.
It is deactivated on the KM-40B, KM-55B, and KM-80B.
When activated, the thermistor detects the temperature of the evaporator outlet to find
overfreeze in a harvest cycle and at the beginning of a freeze cycle. If the difference
between the maximum temperature after the water saver timer starts counting and the
temperature at the end of a harvest cycle is 4K or more and if the temperature at the
end of a harvest cycle is 9°C or less, the harvest cycle is extended for 30 seconds. If the
difference between the temperature at the beginning of a freeze cycle and the minimum
temperature after 30 seconds in the freeze cycle is 2.5K or more and less than 3.5K,
the next harvest cycle is extended for 30 seconds. If the above conditions occur in
succession, the number of occurrence times 30 seconds will be added to the harvest
cycle time. If the above temperature difference is 3.5K or more, the freeze cycle ends
after the minimum freeze cycle time and a harvest cycle starts.
S2 Dip Switch Setting
No. 5
OFF
ON
l) Anti-Slush Control (S2 dip switch 6)
Do not adjust. This must be left in the factory default position or the unit will not operate
properly.
When activated (Ver. 1.1), the thermistor located on the suction line checks for a 5°C
temperature as the evaporator cools. When 5°C is reached, a 4.8 kΩ signal causes the
control board to de-energize the pump motor for 10 seconds.
When activated (Ver. 2.0), the thermistor located on the suction line checks for a 10°C
temperature as the evaporator cools. When 10°C is reached, a 3.9 kΩ signal causes
the control board to de-energize the pump motor for 10 seconds and energize it for 50
seconds repeatedly. When 1°C is reached, a 5.9 kΩ signal causes the control board to
de-energize the pump motor for 10 seconds, energize it for 50 seconds, de-energize it
again for 10 seconds, then energize it continuously.
S2 Dip Switch Setting
No. 6
OFF
ON

[d] CONTROL BOARD CHECK PROCEDURE

Before replacing a control board that does not show a visible defect and that you
suspect is bad, always conduct the following check procedure. This procedure will help
you verify your diagnosis.
Overfreeze Detection
Control
Deactivated
Activated
Anti-Slush Control
Activated (Ver. 1.1)
Activated (Ver. 2.0)
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