Hoshizaki KM-320MAH Service Manual page 10

c) High Temperature Safety - 127 ± 7°F (53 ± 4°C)
The temperature of the suction line in the refrigerant circuit is limited by the high
temperature safety.
During the defrost cycle the evaporator temperature rises. The thermistor senses
48°F (9°C) and starts the defrost timer. After the defrost timer counts down to zero,
the normal freeze cycle begins. If the evaporator temperature continues to rise, the
thermistor will sense the rise in temperature and at 127 ± 7°F (53 ± 4°C) the thermistor
operates the high temperature safety.
This high temperature safety shuts down the circuit and the icemaker automatically
stops.
This high temperature safety protects the unit from excessive temperature. The control
board will beep every 3 seconds. The white reset button on the control board must be
pressed with power on to reset the safety.
d) Low Water Safety
If the pump motor is operated without water, the mechanical seal can fail. To prevent
this type of failure, the controller board checks the position of the float switch at the end
of the initial one minute water fill cycle and at the end of each defrost cycle.
If the float switch is in the up position (electrical circuit closed), the controller board
changes to the ice making cycle. If the float switch is in the down position (electrical
circuit open), the controller board changes to a one minute water fill cycle before
starting the ice making cycle. This method allows for a low water safety shut down to
protect the water pump from mechanical seal failure.
For water-cooled model, if the water is shut off, the unit is protected by the high
pressure switch.
e) High Voltage Cut-out
The maximum allowable supply voltage of this icemaker is limited by the high voltage
cut-out.
If miswiring (especially on single phase 3 wire models) causes excessive voltage on
the controller board, the high voltage cut-out shuts down the circuit in 3 seconds and
the icemaker automatically stops. When the proper supply voltage is resumed, the
icemaker automatically starts running again. The control board will signal this problem
using 7 beeps every 3 seconds.
f) LED Lights and Audible Alarm Safeties
The red LED indicates proper control voltage and will remain on unless a control
voltage problem occurs. At startup a 5 second delay occurs while the board conducts
an internal timer check. A short beep occurs when the power switch is turned ON or
OFF.
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