IV. Service Diagnosis, Diagnostic Procedure | Hoshizaki KM-901MRH/3

IV. Service Diagnosis

WARNING

1.This unit should be diagnosed and repaired only by qualified service personnel to reduce the risk of death, electric shock, serious injury, or fire.

2.Risk of electric shock. Use extreme caution and exercise safe electrical practices.

3.Moving parts (e.g., fan blade) can crush and cut. Keep hands clear.

4.CHOKING HAZARD: Ensure all components, fasteners, and thumbscrews are securely in place after the unit is serviced. Make sure that none have fallen into the storage bin.

5.Make sure all food zones in the icemaker and storage bin are clean after the unit is serviced. For cleaning procedures, see "VI. Cleaning and Maintenance."

A.Diagnostic Procedure

The diagnostic procedure is basically a sequence check which can be used at unit startup or for system diagnosis. This procedure allows you to diagnose electrical system and component failures. Before conducting the diagnostic procedure, check for correct installation, proper voltage per unit nameplate, and adequate water supply. Check

CB using the steps in "IV.B. Control Board Check." Check the dip switch settings to assure that S4 dip switch 3, 4, 7, 8, 9, & 10 and S5 dip switch 1 through 5 ("G" CB) are in the factory default position. S4 dip switch 1, 2, 5, & 6 are cleaning adjustments and the settings are flexible. For factory default settings, see "II.C.3.a) Default Dip Switch Settings." As you go through the procedure, check to assure the components energize and de-energize correctly. If not, those components and controls are suspect.

1)Turn off the power supply, then access the control box. Clear any ice from TBC or MBC.

2)Turn on the power supply, then move the control switch to the "ICE" position. A

5‑second delay occurs. The red "POWER OK" LED on CB comes on. On "G" CB, the green "BC CLOSED" LED also comes on. If the yellow "BC OPEN" LED is on (indicating a full bin), check MBC. See "IV.C.2.a) Mechanical Bin Control Check."

WARNING

1.Risk of electric shock. Use extreme caution and exercise safe electrical practices.

2.Moving parts (e.g., fan blade) can crush and cut. Keep hands clear.

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Hoshizaki KM-901MRH/3, KM-901MWH, KM-901MAH service manual IV. Service Diagnosis, Diagnostic Procedure

Contents

KM-901MAH KM-901MWH Hoshizaki AMERICA, INC Contents Page Page Indicates important information about the use and care Important Safety InformationSerious injury Unit Specifications Icemaker 1a. KM-901MAH air-cooled Auxiliary Code T-0, U-0 1b. KM-901MAH air-cooled Auxiliary Code U-1 and Later 2a. KM-901MWH water-cooled Auxiliary Code T-0, U-0 Water Cooled Condenser 2b. 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 Specifications Model URC-9F II. General Information Construction KM-901MAH air-cooled KM-901MWH water-cooled KM-901MRH/3 remote air-cooled Control Board Auxiliary Code T-0, U-0 Sequence of OperationSequence Cycles and Shutdown Shutdown Control Board Auxiliary Code U-1 and Later OFF Cycle at Shutdown Mechanical Bin Control Activation Cycle Control Board Sequence Flow ChartSequence Flow Chart Bin Full Minute Harvest Cycle Freeze Cycle Pump-Out Cycle Control Board Auxiliary Code U-1Later Fill Cycle Control Board Control Board Layout Control Board Part Number 2A3792-01 Low Water Safety Harvest Backup Timer and Freeze TimerHigh Temperature Safety Maximum Water Supply Period 6 minutes Sequence Step LED Lights and Audible Alarm SafetiesNo. of Beeps Type of Alarm Every 3 sec Energized Time LEDs are On Components Min Max Avg Control Board Auxiliary Code U-1 and Later Harvest Timer S4 dip switch 1 Controls and AdjustmentsDefault Dip Switch Settings S4 Dip Switch S4 Dip Switch No S4 Dip Switch Setting Time seconds Inlet Pump-Out Timer S4 dip switch 3Pump-Out Frequency Control S4 dip switch 5 Control Board S4 Dip Switch Setting Bin Control Bin Control Selector/Harvest Pump Timer S4 dip switchFactory Use S4 dip switch Control Board S4 Dip Switch Setting Pump Motor Time seconds Refill Counter S5 dip switch 2 through 5 G Control Board Freeze Timer S4 dip switch 9Float Switch Control S5 dip switch 1 G Control Board S4 Dip Switch Setting Time Minutes Bin Control Float SwitchControl Switch Thermistor Water Pump Switch Discharge Line KM-901MAH air-cooled and KM-901MWH water-cooled Wiring DiagramsModelCooled-AirWater-Cooled Model PressureHigh* Switch High PressureSwitchKM-901MRH remote air-cooled KM-901MRH3 remote air-cooled Switch Cooled-WaterModel Cooled-AirModel High* Pressure High Pressure Switch SwitchPressure Performance Data 1480 912835 1570 KM-901MRH remote air-cooled KM-901MRH3 remote air-cooled IV. Service Diagnosis Diagnostic ProcedurePage OFF Control Board Check Shutdown Thermostatic Bin Control Auxiliary Code T-0, U-0 Bin Control Check Control Correct LED Board Lighting Sequence Mechanical Bin Control Check Mechanical Bin Control Cleaning Float Switch Check and Cleaning Float Switch Check Float Switch Cleaning Thermistor Check No Ice Production Diagnostic ChartsProblem Possible Cause Remedy Problem Possible Cause Remedy Problem Possible Cause Remedy Evaporator is Frozen Up Problem Possible Cause Remedy Low Ice Production Abnormal Ice Other Refrigerant Recovery Removal and Replacement of ComponentsService for Refrigerant Lines Brazing Evacuation and Recharge R-404A Removal 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 VI. Cleaning and Maintenance Cleaning and Sanitizing Instructions Cleaning Procedure Sanitizing Procedure Following Cleaning Procedure Maintenance Preparing the Icemaker for Long Storage Drain the water tank