Hoshizaki KM-420MWJ User manual

Models
KM-350MAJ, MWJ
KM-420MAJ, MWJ, MRJZ
KM-520MAJ, MWJ, MRJ(Z)
KM-660MAJ, MWJ, MRJ(Z)
Modular Crescent Cuber
Service Manual
Number: 73230
Issued: 10-29-2018
Revised: 11-7-2023
hoshizakiamerica.com

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WARNING
Only qualied service technicians should install and service the appliance.
To obtain the name and phone number of your local Hoshizaki Certied Service
Representative, visit www.hoshizaki.com. No service should be undertaken until
the technician has thoroughly read this Service Manual. Failure to service and
maintain the appliance in accordance with this manual will adversely affect safety,
performance, component life, and warranty coverage. Proper installation is the
responsibility of the installer. Product failure or property damage due to improper
installation is not covered under warranty.
Hoshizaki provides this manual primarily to assist qualied service technicians in the
service of the appliance.
Should the reader have any questions or concerns which have not been satisfactorily
addressed, please call, send an e-mail message, or write to the Hoshizaki Technical
Support Department for assistance.
Phone: [phone]
Fax: [phone]
E-mail: [email protected]
618 Highway 74 South
Peachtree City, GA 30269
Attn: Hoshizaki Technical Support Department
Web Site: www.hoshizaki.com
NOTE: To expedite assistance, all correspondence/communication MUST include the
following information:
• Model Number
• Serial Number
• Complete and detailed explanation of the problem.

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CONTENTS
Important Safety Information ................................................................................................. 5
I. Construction and Water/Refrigeration Circuit Diagrams ..................................................... 7
A. Construction.................................................................................................................. 7
1. Air-Cooled Models (MAJ) ......................................................................................... 7
2. Water-Cooled Models (MWJ)................................................................................... 8
3. Remote Models (MRJ, MRJZ ) ................................................................................ 9
B. Water/Refrigeration Circuit Diagrams .......................................................................... 10
1. Air-Cooled Models (MAJ) ....................................................................................... 10
2. Water-Cooled Models (MWJ)..................................................................................11
3. Remote Models (MRJ, MRJZ) ............................................................................... 12
II. Sequence of Operation and Service Diagnosis............................................................... 13
A. Sequence of Operation Flow Charts........................................................................... 13
1. Operation Flow Chart ............................................................................................ 13
2. Shutdown Flow Chart ............................................................................................ 14
B. Service Diagnosis ....................................................................................................... 15
1. K Control Board (2A8242-02) with Ultrasonic Bin Control ..................................... 15
2. K Control Board (2A8242-02) with Mechanical Bin Control................................... 22
3. K+ Control Board (2A9678-01) with Ultrasonic Bin Control ................................... 29
C. Control Board Check................................................................................................... 36
D. Bin Control Check, Adjustment, and Cleaning ............................................................ 38
E. Float Switch Check and Cleaning ............................................................................... 44
F. Thermistor Check......................................................................................................... 46
G. Control Switch............................................................................................................. 46
H. Mode Switch ............................................................................................................... 46
I. Diagnostic Tables.......................................................................................................... 47
J. Freeze-Up Check List .................................................................................................. 51
III. Controls and Adjustments............................................................................................... 52
A. Control Board Layout .................................................................................................. 53
1. K Control Board (2A8242-02)................................................................................. 53
2. K+ Control Board (2A9678-01) .............................................................................. 54
B. LED Lights and Audible Alarm Safeties....................................................................... 55
1. K Control Board (2A8242-02)................................................................................. 55
2. K+ Control Board (2A9678-01) .............................................................................. 56
C. Settings and Adjustments............................................................................................ 57
1. Default Dip Switch Settings .................................................................................... 57
2. Harvest Time (S4 dip switch 1 & 2)........................................................................ 58
3. Pump-Out Time/Harvest Time During Pump-Out (S4 dip switch 3 & 4)................. 58
4. Pump-Out Frequency Control (S4 dip switch 5)..................................................... 59
5. Harvest Pump Time (Harvest Assist) (S4 dip switch 6) ......................................... 59
6. Harvest Pump Time (Harvest Assist (S4 dip switch 7) .......................................... 60
IMPORTANT
This manual should be read carefully before the appliance is serviced. Read
the warnings and guidelines contained in this manual carefully as they provide
essential information for the continued safe use, service, and maintenance of the
appliance. Retain this manual for any further reference that may be necessary.

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7. Factory Use (S4 dip switch 8)................................................................................. 60
8. Freeze Timer (S4 dip switch 9 & 10) ...................................................................... 60
9. Float Switch Selector (S5 dip switch 1) ................................................................. 61
10. Rell Counter (S5 dip switch 2 and 3).................................................................. 61
11. Minimum Harvest Time (S5 dip switch 4) ............................................................. 61
12. Anti-Slush (S5 dip switch 5)................................................................................. 62
IV. Refrigeration Circuit and Component Service Information.............................................. 63
A. Refrigeration Circuit Service Information ................................................................... 63
B. Refrigeration Circuit Service Information ................................................................... 66
C. Component Service Information ................................................................................. 69
D. Water Regulating Valve Adjustment (water-cooled model) .......................................... 69
V. Maintenance .................................................................................................................... 70
VI. Preparing the Appliance for Periods of Non-Use ............................................................ 71
VII. Disposal......................................................................................................................... 73
VIII. Technical Information.....................................................................................................74
A. Specication and Performance Data Sheets................................................................74
1. KM-350MAJ ............................................................................................................74
2. KM-350MWJ.......................................................................................................... 75
3. KM-420MAJ........................................................................................................... 76
4. KM-420MWJ.......................................................................................................... 77
5. KM-420MRJZ with URC-5FZ................................................................................. 78
6. KM-520MAJ........................................................................................................... 79
7. KM-520MWJ .......................................................................................................... 80
8. KM-520MRJ with URC-5F ..................................................................................... 81
9. KM-520MRJZ with URC-5FZ................................................................................. 82
10. KM-660MAJ ......................................................................................................... 83
11. KM-660MWJ......................................................................................................... 84
12. KM-660MRJ with URC-5F ................................................................................... 85
13. KM-660MRJZ with URC-5FZ............................................................................... 86
B. Wiring Diagrams ......................................................................................................... 87
1. K Control Board (2A8242-02) with Ultrasonic Bin Control ..................................... 87
2. K Control Board (2A8242-02) with Mechanical Bin Control................................... 88
3. K+ Control Board (2A9678-01) with Ultrasonic Bin Control ................................... 89

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Important Safety Information
Throughout this manual, notices appear to bring your attention to situations which could
result in death, serious injury, damage to the appliance, or damage to property.
WARNING Indicates a hazardous situation which could result in death or
serious injury.
NOTICE Indicates a situation which could result in damage to the
appliance or property.
IMPORTANT Indicates important information about the use and care of the
appliance.
WARNING
The appliance should be destined only to the use for which it has been expressly
conceived. Any other use should be considered improper and therefore dangerous.
The manufacturer cannot be held responsible for injury or damage resulting from
improper, incorrect, and unreasonable use. Failure to service and maintain the
appliance in accordance with this manual will adversely affect safety, performance,
component life, and warranty coverage and may result in costly water damage.
To reduce the risk of death, electric shock, serious injury, or re, follow basic
precautions including the following:
• Only qualied service technicians should install and service this appliance.
• The appliance must be installed in accordance with applicable national, state, and
local codes and regulations.
• Electrical connection must be hard-wired and must meet national, state, and local
electrical code requirements. Failure to meet these code requirements could result
in death, electric shock, serious injury, re, or severe damage to equipment.
• The icemaker requires an independent power supply of proper capacity. See the
nameplate for electrical specications. Failure to use an independent power supply
of proper capacity can result in a tripped breaker, blown fuses, damage to existing
wiring, or component failure. This could lead to heat generation or re.
• THE ICEMAKER MUST BE GROUNDED. Failure to properly ground the icemaker
could result in death or serious injury.
• Move the control switch to the "OFF" position and turn off the power supply before
servicing. Lockout/Tagout to prevent the power supply from being turned back on
inadvertently.
• To reduce the risk of electric shock, do not touch the control switch with damp
hands.
• Do not make any alterations to the unit. Alterations could result in electric shock,
injury, re, or damage to the unit.
• The appliance is not intended for use by persons (including children) with reduced
physical, sensory, or mental capabilities, or lack of experience and knowledge,
unless they have been given supervision or instruction concerning use of the
appliance by a person responsible for their safety.

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WARNING, continued
• Children should be properly supervised around this appliance.
• Do not climb, stand, or hang on the appliance or allow children or animals to do so.
Serious injury could occur or the appliance could be damaged.
• Do not use combustible spray or place volatile or ammable substances near the
appliance. They might catch re.
• Keep the area around the appliance clean. Dirt, dust, or insects in the appliance
could cause harm to individuals or damage to the appliance.
Additional Warning for Remote Models
• THE REMOTE CONDENSER UNIT MUST BE GROUNDED. The power supply and
ground connection to the remote condenser unit are supplied from the icemaker.
Failure to properly ground the remote condenser unit could result in death or
serious injury.
• Move the icemaker control switch to the "OFF" position and turn off the power
supply to the icemaker before servicing the remote condenser unit.
Lockout/Tagout to prevent the power supply from being turned back on
inadvertently.
NOTICE
• Follow the instructions in this manual carefully to reduce the risk of costly water
damage.
• In areas where water damage is a concern, install in a contained area with a oor
drain.
• Install the appliance in a location that stays above freezing. Normal operating
ambient temperature must be within 45°F to 100°F (7°C to 38°C).
• Do not leave the icemaker on during extended periods of non-use, extended
absences, or in sub-freezing temperatures. To properly prepare the icemaker for
these occasions, follow the instructions in "VI. Preparing the Appliance for Periods
of Non-Use."
• Do not place objects on top of the appliance.
• The dispenser unit/ice storage bin is for ice use only. Do not store anything else in
the dispenser unit/ice storage bin.

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I. Construction and Water/Refrigeration Circuit Diagrams
A. Construction
1. Air-Cooled Models (MAJ)
Model Shown: KM-350MAJ
Water Supply Inlet
Condenser
Drier
Control Box
Spray Tubes
Control Switch
Water Pump
Float Switch
Compressor
Thermostatic
Expansion Valve Fan Motor
Hot Gas Valve
Cleaning Valve
*Ultrasonic Bin
Control Sensor
Inlet Water Valve High-Pressure
Switch
Liquid Line
Valve
Evaporator
Strainer
Mode Switch
Drain Valve
Mechanical
Bin Control
Extension
Bracket (ABS)
**Mechanical
Bin Control
Mechanical Bin
Control Bracket
(SUS)
Model
Bin Control Auxiliary Code Break
*Ultrasonic Bin Control Sensor **Mechanical Bin Control
KM-350MAJ L19076J and earlier, L19237K and later L19077K to L19236K
KM-420MAJ ALL -
KM-520MAJ L02152J and earlier, L02412K and later L02153K to L02411K
KM-660MAJ L05261J and earlier, L15442L and later L05262K to L05441K

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2. Water-Cooled Models (MWJ)
Water Supply Inlet
Condenser
Drier
Control Box
Spray Tubes
Control Switch
Water Pump
Float Switch
Compressor
Thermostatic
Expansion
Valve
Water Regulating
Valve
Hot Gas Valve
Cleaning Valve
Model Shown: KM-520MWJ
Inlet Water
Valve
Liquid Line Valve
High-Pressure Switch
Evaporator Strainer
Mode Switch
Drain Valve
*Ultrasonic Bin
Control Sensor
Mechanical
Bin Control
Extension
Bracket (ABS)
**Mechanical
Bin Control
Mechanical Bin
Control Bracket
(SUS)
Model
Bin Control Auxiliary Code Break
*Ultrasonic Bin Control Sensor **Mechanical Bin Control
KM-350MWJ H-0 and later -
KM-420MWJ ALL -
KM-520MWJ H-0 and later -
KM-660MWJ L00673J and earlier, L10694L and later L00674K to L00693K

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3. Remote Models (MRJ, MRJZ )
Receiver Tank
Water Supply Inlet
Drier
Spray Tubes
Control Switch
Water Pump
Float Switch
Compressor
Thermostatic
Expansion Valve
Hot Gas Valve
Liquid Line Valve
Cleaning Valve
Model Shown: KM-660MRJ
Inlet Water
Valve
Crankcase Heater
Strainer
High-Pressure
Switch
Evaporator
Control Box
Mode Switch
Drain Valve
MRJZ
Discharge and Liquid
Line Connections
(OS Quick Connector)
MRJ
Discharge and
Liquid Line
Service Valves
Ultrasonic Bin
Control Sensor
Auxiliary Code
H-0 and later

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B. Water/Refrigeration Circuit Diagrams
1. Air-Cooled Models (MAJ)
Water Supply
Float Switch
Drain
Thermostatic Expansion Valve
Compressor
Hot Gas Valve
High-Pressure Switch
Strainer
Fan
Drier
Condenser
Evaporator
Discharge Line
Suction Line
Water Pump
Thermistor
Spray Tubes
Inlet Water Valve
Water Tank
Refrigeration Circuit
Water Circuit
Heat Exchanger
Liquid Line Valve
Cleaning Valve
Drain Valve