Hoshizaki KM-901MWH, KM-901MAH, KM-901MRH/3 service manual Evaporator is Frozen Up

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Problem	Possible Cause		Remedy

[7] Fan motor will	a) Fan Motor	1. Motor winding open.	1. Replace.
not start, or is not		2. Bearing worn out.	2. Replace.
operating (except		2. Bearing worn out.	2. Replace.

		3. Wiring to fan motor.	3. Check for loose connection
water-cooled model).		3. Wiring to fan motor.	3. Check for loose connection
water-cooled model).			or open, and replace.
			or open, and replace.

		4. Defective capacitor.	4. Replace.

		5. Fan blade bound.	5. Check and replace.
	b) Control Board	1. Defective.	1. See "IV.B. Control Board
			Check."
[8] All components	a) Refrigerant	1. Low charge.	1. Check for leaks. Recover,
run, but no ice is			repair, evacuate, and
produced.			recharge.

		2. Air or moisture	2. Recover, replace drier,
		trapped.	evacuate, and recharge.

	b) Compressor	1. Defective.	1. Replace.

	c) Hot Gas Valve	1. Continues to open in	1. Check and replace.
		freeze cycle.
	d) Liquid Line Valve	1. Continues to close in	1. Check and replace.
	(if applicable)	freeze cycle.

	e) Inlet Water Valve	1. Inlet water valve is	1. Check for water leaks with
		wide open during	icemaker off.
		freeze.

	f) Expansion Valve	1. Bulb loose.	1. Secure bulb.

		2. Operating erratically.	2. Check and replace.
	g) Headmaster (C.P.R.)	1. Not operating properly	1. Replace headmaster.
	(remote condenser	and liquid line
	unit)	temperature too warm.

	h) Water Supply Line	1. Condenser water	1. Check and get
	(water-cooled model)	pressure too low or	recommended pressure.
		off and high pressure
		control opens and
		closes frequently.

	i) Water Regulating Valve	1. Set too high.	1. Adjust or replace. See
	(water-cooled model)		"V.J. Adjustment of Water
			Regulating Valve."

2. Evaporator is Frozen Up

Problem	Possible Cause		Remedy

[1]Freeze cycle time is	a) Inlet Water Valve	1. Diaphragm does not	1. Check for water leaks with
too long.		close.	icemaker off.

	b) Float Switch	1. Float does not move	1. Clean or replace. See "IV.
		freely or defective	D. Float Switch Check and
		switch.	Cleaning."

	c) Evaporator	1. Scaled up.	1. Clean.
		2. Damaged.	2. Replace.

	d) Spray Tubes	1. Dirty.	1. Clean.

		2. Out of position.	2. Place in position.

	e) Pump Motor	1. RPM too slow.	1. See chart 1.[5].

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Contents KM-901MAH KM-901MWH Hoshizaki AMERICA, INC Contents Page Page Unit Important Safety InformationSerious injury Indicates important information about the use and care1a. KM-901MAH air-cooled Auxiliary Code T-0, U-0 Specifications Icemaker1b. KM-901MAH air-cooled Auxiliary Code U-1 and Later Water Cooled Condenser 2a. KM-901MWH water-cooled Auxiliary Code T-0, U-02b. KM-901MWH water-cooled Auxiliary Code U-1 and Later 3a. KM-901MRH remote air-cooled Auxiliary Code T-0, U-0 3b. KM-901MRH remote air-cooled Auxiliary Code U-1 and Later 4a. KM-901MRH3 remote air-cooled Auxiliary Code T-0, U-0 4b. KM-901MRH remote air-cooled Auxiliary Code U-1 and Later Condenser Unit Model URC-9F SpecificationsKM-901MAH air-cooled II. General Information ConstructionKM-901MWH water-cooled KM-901MRH/3 remote air-cooled Sequence of Operation Sequence Cycles and ShutdownControl Board Auxiliary Code T-0, U-0 Control Board Auxiliary Code U-1 and Later ShutdownOFF Cycle at Shutdown Mechanical Bin Control Activation Bin Full Control Board Sequence Flow ChartSequence Flow Chart CycleFill Cycle Control Board Auxiliary Code U-1Later Minute Harvest Cycle Freeze Cycle Pump-Out CycleControl Board Control Board Control Board LayoutPart Number 2A3792-01 Maximum Water Supply Period 6 minutes Harvest Backup Timer and Freeze TimerHigh Temperature Safety Low Water SafetyEnergized Time LEDs are On Components Min Max Avg LED Lights and Audible Alarm SafetiesNo. of Beeps Type of Alarm Every 3 sec Sequence StepControl Board Auxiliary Code U-1 and Later S4 Dip Switch S4 Dip Switch No Controls and AdjustmentsDefault Dip Switch Settings Harvest Timer S4 dip switch 1Pump-Out Timer S4 dip switch 3 Pump-Out Frequency Control S4 dip switch 5S4 Dip Switch Setting Time seconds Inlet Control Board S4 Dip Switch Setting Pump Motor Time seconds Bin Control Selector/Harvest Pump Timer S4 dip switchFactory Use S4 dip switch Control Board S4 Dip Switch Setting Bin ControlS4 Dip Switch Setting Time Minutes Freeze Timer S4 dip switch 9Float Switch Control S5 dip switch 1 G Control Board Refill Counter S5 dip switch 2 through 5 G Control BoardThermistor Float SwitchControl Switch Bin ControlWater Pump Switch Discharge Line Wiring Diagrams ModelCooled-AirWater-Cooled Model PressureHigh* SwitchKM-901MAH air-cooled and KM-901MWH water-cooled PressureSwitch KM-901MRH remote air-cooledHigh KM-901MRH3 remote air-cooled Cooled-AirModel High* Pressure Switch Cooled-WaterModelHigh Pressure Switch SwitchPressure Performance Data 1570 912835 1480KM-901MRH remote air-cooled KM-901MRH3 remote air-cooled Diagnostic Procedure IV. Service DiagnosisPage OFF Shutdown Thermostatic Bin Control Auxiliary Code T-0, U-0 Control Board CheckControl Correct LED Board Lighting Sequence Bin Control CheckMechanical Bin Control Check Mechanical Bin Control Cleaning Float Switch Check Float Switch Check and CleaningFloat Switch Cleaning Thermistor Check Diagnostic Charts Problem Possible Cause RemedyNo Ice Production Problem Possible Cause Remedy Problem Possible Cause Remedy Evaporator is Frozen Up Problem Possible Cause Remedy Low Ice Production Abnormal Ice Other Removal and Replacement of Components Service for Refrigerant LinesRefrigerant Recovery Evacuation and Recharge R-404A BrazingRemoval and Replacement of Compressor Removal and Replacement of Expansion Valve Page Removal and Replacement of Evaporator Removal and Replacement of Air-Cooled Condenser Removal and Replacement of Water-Cooled Condenser Removal and Replacement of Remote Air-Cooled Condenser Page Adjustment of Water Regulating Valve water-cooled model Removal and Replacement of Thermistor Removal and Replacement of Inlet Water Valve Removal and Replacement of Pump Motor Removal and Replacement of Control Board Cleaning and Sanitizing Instructions VI. Cleaning and MaintenanceCleaning Procedure Sanitizing Procedure Following Cleaning Procedure Preparing the Icemaker for Long Storage MaintenanceDrain the water tank