Hoshizaki KM-280MWF, KM-280MAF SERVICE MANUAL

NO.:
ISSUED:
REVISED:

73084

MAY 25, 1999

DEC. 13, 2003

HOSHIZAKI

MODULAR CRESCENT CUBER

MODEL

KM-280MAF
KM-280MWF

SERVICE MANUAL

IMPORTANT

Only qualified service technicians should attempt to service or maintain this icemaker.
No service or maintenance should be undertaken until the technician has thoroughly
read this Service Manual.

HOSHIZAKI provides this manual primarily to assist qualified service technicians in the
service and maintenance of the icemaker.

Should the reader have any questions or concerns which have not been satisfactorily
addressed, please call or write to the HOSHIZAKI Technical Support Department for
assistance.

HOSHIZAKI AMERICA, INC.
618 Highway 74 South
Peachtree City , GA 30269

Attn: HOSHIZAKI T echnical Support Department

Phone: [phone] T echnical Service

[phone]

Fax: [phone]

NOTE: T o expedite assistance, all correspondence/communication MUST include the following

information:

• Model Number

• Serial Number

• Complete and detailed explanation of the problem

2

• Please review this manual. It should be read carefully before the icemaker is serviced
or maintenance operations performed. Only qualified service technicians should service
and maintain the icemaker. This manual should be made available to the technician
prior to service or maintenance.

CONTENTS

PAGE

I. SPECIFICATIONS .................................................................................................... 5

1. KM-280MAF (Air-cooled) .................................................................................... 5

2. KM-280MWF (Water-cooled) .............................................................................. 6

II. GENERAL INFORMATION ...................................................................................... 7

1. CONSTRUCTION ............................................................................................... 7

[a] KM-280MAF .................................................................................................. 7

[b] KM-280MWF ................................................................................................. 8

2. CONTROLLER BOARD...................................................................................... 9

[a] SOLID-STATE CONTROL ............................................................................ 9

[b] CONTROLLER BOARD................................................................................ 9

[c] SEQUENCE................................................................................................ 13

[d] CONTROLS AND ADJUSTMENTS ........................................................... 1 6

[e] CHECKING CONTROLLER BOARD ......................................................... 1 9

III. TECHNICAL INFORMATION............................................................................... 21

1. WATER CIRCUIT AND REFRIGERANT CIRCUIT.......................................... 21

[a] KM-280MAF ................................................................................................ 21

[b]KM-280MWF ................................................................................................ 22

2. WIRING DIAGRAMS......................................................................................... 23

3. TIMING CHART ................................................................................................ 24

4. PERFORMANCE DATA ................................................................................... 26

[a] KM-280MAF (Air-cooled)............................................................................. 26

[b] KM-280MWF (Water-cooled)....................................................................... 27

IV. SERVICE DIAGNOSIS ........................................................................................ 28

1. NO ICE PRODUCTION..................................................................................... 28

2. EVAPORATOR IS FROZEN UP....................................................................... 31

3. LOW ICE PRODUCTION .................................................................................. 32

4. ABNORMAL ICE............................................................................................... 32

5. OTHERS ........................................................................................................... 32

3

V. REMOVAL AND REPLACEMENT OF COMPONENTS ...........................................33

1. SERVICE FOR REFRIGERANT LINES.................................................................33

[a] REFRIGERANT RECOVERY ........................................................................33

[b] EVACUATION AND RECHARGE...................................................................33

2. BRAZING .............................................................................................................34

3. REMOVAL AND REPLACEMENT OF COMPRESSOR .......................................35

4. REMOVAL AND REPLACEMENT OF DRIER ......................................................36

5. REMOVAL AND REPLACEMENT OF EXPANSION VALVE ...............................37

6. REMOVAL AND REPLACEMENT OF HOT GAS VALVE ........................................

AND/OR LINE VALVE..........................................................................................38

7. REMOVAL AND REPLACEMENT OF EVAPORATOR ........................................39

8. REMOVAL AND REPLACEMENT OF WATER-REGULATING VALVE .................

- WATER COOLED MODEL ONLY.....................................................................40

9. ADJUSTMENT OF WATER-REGULATING VALVE ...............................................

- WATER COOLED MODEL ONLY.....................................................................41

10. REMOVAL AND REPLACEMENT OF THERMISTOR ........................................ 42

11. REMOVAL AND REPLACEMENT OF FAN MOTOR........................................... 43

12. REMOVAL AND REPLACEMENT OF WATER VALVE ...................................... 44

13. REMOVAL AND REPLACEMENT OF PUMP MOTOR........................................44

14. REMOVAL AND REPLACEMENT OF SPRAY TUBE.........................................45

VI. MAINTENANCE AND CLEANING INSTRUCTIONS .............................................46

1. PREPARING THE ICEMAKER FOR LONG STORAGE......................................4 6

2. CLEANING AND SANITIZING PROCEDURES .................................................. 48

[a] CLEANING PROCEDURE ............................................................................49

[b] SANITIZING PROCEDURE...........................................................................5 0

3. MAINTENANCE...................................................................................................51

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I. SPECIFICATIONS

1. KM-280MAF (Air-cooled)

* We reserve the right to make changes in specifications and design without prior notice.

5

2. KM-280MWF (Water-cooled)

* We reserve the right to make changes in specifications and design without prior notice.

6

II. GENERAL INFORMATION

1. CONSTRUCTION

[a] KM-280MAF

Spray Tube Water Supply Inlet

Control Switch

Bin Control
Thermostat Hot Gas Valve

Condenser

Expansion Valve Fan Motor,

Condenser

Compressor

Drier

Float Switch

Control Box

Water Pump

7

[b] KM-280MWF

Spray Tube Water Supply Inlet

Control Switch

Water Regulator

Bin Control

Thermostat

Expansion Valve Hot Gas Valve

Compressor
Float Switch Drier

Water Pump Control Box

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2. CONTROLLER BOARD

[a] SOLID-STATE CONTROL

1) A HOSHIZAKI exclusive solid-state control is employed in KM-280MAF, KM-280MWF
Modular Crescent Cubers.

2) A Printed Circuit Board (hereafter called “Controller Board”) includes a stable and high
quality control system.

3) All models are pretested and factory-adjusted.

[b] CONTROLLER BOARD

CAUTION

1. Fragile, handle very carefully.

2. A controller board contains integrated circuits, which are susceptible to
failure due to static discharge. It is especially important to touch the metal
part of the unit when handling or replacing the board.

3. Do not touch the electronic devices on the board or the back of the board
to prevent damage to the board.

4. Do not change wiring and connections. Do not misconnect K3, K4 and K5,
because the same connector is used for the Thermistor and Float Switch.
K4 is not connected.

5. Always replace the whole board assembly when it goes bad.

6. Do not short out power supply to test for voltage.

PART NUMBER TYPE

2A1410-01 HOS-001A (Control Products)

Features of Control Products “E” Controller Board

1) Maximum Water Supply Period - 6 minutes
Water Solenoid Valve opening, in the Defrost (Harvest) Cycle, is limited by the defrost

timer. The Water Valve cannot remain open longer than the maximum period. The
Water Valve can close in less than six minutes if the defrost cycle is completed.

9

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 Tem­perature 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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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.

The green LED’s 1-4 represent the corresponding relays and energize and sequence 5
seconds from initial startup as follows:

Sequence Step LED’s on Length: Min. Max. Avg.

1 Minute Fill Cycle LED4 60 sec.
Harvest Cycle LED1, 4, & 2 2 min. 20 min. 3-5 min.
Freeze Cycle LED1 5 min. 60 min. 30-35 min.
Reverse Pump Out LED1, 3, & 2 10 sec. 20 sec. Factory set.

{LED 1 – Comp; LED 2 - HGV/CFM; LED 3 – PM; LED 4 - WV}
The built in safeties shut down the unit and have alarms as follows:

1 beep every 3 sec. = High Evaporator Temperature >127 ° F.
Check for defrost problem (stuck HGV or relay), hot water entering unit, stuck headmas-

ter, or shorted thermistor.
2 beeps every 3 sec. = Defrost Back Up Timer. Defrost >20 minutes.

Orange LED marked 20 MIN energizes.
Check for open thermistor, HGV not opening, TXV leaking by, low charge, or inefficient
compressor.

3 beeps every 3 sec. = Freeze Back Up Timer. Freeze > 60 minutes.
Yellow LED marked 60 MIN energizes.
Check for F/S stuck closed (up), WV leaking by, HGV leaking by, TXV not feeding prop­erly, low charge, or inefficient compressor.

To manually reset the above safeties, depress white alarm reset button with the power
supply ON.

6 beeps every 3 sec. = Low Voltage. Voltage is 92 Vac or less.
7 beeps every 3 sec. = High Voltage. Control voltage > 147Vac ±5%.

The red LED will de-energize if voltage protection operates.
The voltage safety automatically resets when voltage is corrected.

The Output Test switch “S3” provides a relay sequence test. With power OFF, place S3
ON and switch power to ICE. The correct lighting sequence should be none, 2, 3, 4, 1, & 4,
normal sequence every 5 seconds. S3 should remain in the “OFF” position for normal
operation.

The application switch located between relay X3 & X4 must be set to match the original
board application. Place this switch in the ALP position if there is no white wire supplied

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to the K1 connector. If there is a white wire, place the switch in the C position. If this
switch is placed in the wrong position either the compressor contactor will remain ener­gized with the control switch OFF or the unit will not start.

The dip switches should be adjusted per the adjustment chart published in the Tech
Specs book. 7 & 8 must remain in the OFF position.

(Control Products HOS-001A Board)

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[c] SEQUENCE

1st Cycle

1. Unit energized and Control Switch to “ICE”
position. Water supply cycle starts.

2. After 1 minute,
Defrost cycle starts.

3. Thermistor reads 48° F.
Defrost Timer starts counting.

5. After the first 5 minutes in freeze cycle.
Ready to complete freeze cycle when Float
Switch circuit opens.

IMPORTANT

Board never accepts freeze completion signal
within the first 5 minutes in freeze cycle.

IMPORTANT

Water Valve
opening is limited
to 6 minutes.

4. Defrost Timer stops counting.
Defrost cycle is completed, freeze cycle
starts and Line Valve opens.

IMPORTANT

1. Board never accepts defrost completion
signal within the first 2 minutes in defrost
cycle.

2. Defrost cycle time is limited to 20 minutes
even if Defrost Timer does not stop counting.

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2nd Cycle and after with pump drain

IMPORTANT

Freeze cycle time is limited to 60 minutes even
if Float Switch does not open.

1. Float Switch opens and signals to complete
freeze cycle.
Drain timer starts counting.

2. Drain timer stops counting.
Pump drain is completed

3. Thermistor reads 48° F.
Defrost Timer starts
counting.

IMPORTANT

Water Valve
opening is limited to 6
minutes.

5. After the first 5 minutes in freeze cycle.
Ready to complete freeze cycle when Float
Switch circuit opens.

IMPORTANT

Board never accepts freeze completion signal
within the first 5 minutes in freeze cycle.

4. Defrost Timer stops counting.
Defrost cycle is completed, freeze cycle
starts and Line Valve opens.

IMPORTANT

1. Board never accepts defrost completion
signal within the first 2 minutes in defrost
cycle.

2. Defrost cycle time is limited to 20 minutes
even if Defrost Timer does not stop counting.

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2nd Cycle and after with no pump drain

IMPORTANT

Freeze cycle time is limited to 60 minutes even
if Float Switch does not open.

1. Float Switch opens and signals to complete
freeze cycle.

2. Thermistor reads 48° F.
Defrost Timer starts counting.

IMPORTANT

Water Valve
opening is limited to 6
minutes.

4. After the first 5 minutes in freeze cycle.
Ready to complete freeze cycle when Float
Switch circuit opens.

IMPORTANT

Board never accepts freeze completion signal
within the first 5 minutes in freeze cycle.

3. Defrost Timer stops counting.
Defrost cycle is completed, freeze cycle
starts and Line Valve opens.

IMPORTANT

1. Board never accepts defrost completion
signal within the first 2 minutes in defrost
cycle.

2. Defrost cycle time is limited to 20 minutes
even if Defrost Timer does not stop counting.

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[d] CONTROLS AND ADJUSTMENTS

The Dip Switch is factory-adjusted to the following positions:

DIP SWITCH NO. 1 2 3 45678910

KM-280MAF ON OFF OFF ON ON ON OFF OFF OFF OFF
KM-280MWF OFF OFF OFF ON ON ON OFF OFF OFF OFF

Switch Nos. 1 and 2:

Used for adjustment of the Defrost Timer.
The Defrost Timer starts counting when the Thermistor reads a certain temperature

at the Evaporator outlet.
Switch Nos. 3 and 4:

Used for adjustment of the Drain Timer.

When a freeze cycle is completed, the Pump Motor stops, and the icemaker
resumes operation in 2 seconds. Then the Pump Motor drains the Water Tank
for the time determined by the Drain Timer. The Drain Timer also determines the
time to restrain completion of a defrost cycle, i.e. the minimum defrost time.

Switch Nos. 5 and 6:

Used for adjustment of the Drain Counter.

The Pump Motor drains the Water Tank at the frequency determined by the Drain
Counter.

Switch Nos. 7 and 8:
Used only for checking the Controller Board. Usually set in OFF position.

Switch Nos. 9 and 10:

Used for adjustment of Freeze Timer.
The Freeze Timer determines maximum
freeze cycle time. Upon termination of
Freeze Timer, machine initiates the
harvest cycle. After 2 consecutive timer
terminations, machine will shut down,
possibly indicating a problem.

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