Hoshizaki KM-900MRF Defrost Timer, High Temperature Safety - 127 ± 7F, Low Water Safety

2)Defrost Timer

The defrost cycle starts when the Float Switch opens and completes the freeze cycle. But the Defrost Timer does not start counting until the Thermistor senses 48°F at the Evaporator outlet. The period from the end of the freeze cycle up to the point of the Thermistor's sensing varies depending on the ambient and water temperatures.

3)High Temperature Safety - 127 ± 7°F

The temperature of the suction line in the refrigerant circuit is limited by the High Tem- perature Safety.

During the defrost cycle the Evaporator temperature rises. The Thermistor senses 48°F 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 the Thermistor operates the High Tem- perature Safety.

This High Temperature Safety shuts down the circuit and the icemaker automatically stops. To reset the safety, turn the power off and back on again.

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.

4)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.

5)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.

6)LED Lights and Audible Alarm Safeties

The red LED indicates proper control voltage and will remain on unless a control voltage

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