Hoshizaki KM-280MAF User manual

NO.:
ISSUED:
REVISED: MAY 25, 1999
73084
HOSHIZAKI
MODULAR CRESCENT CUBER
MODEL
DEC.13,2003
KM-280MAF
KM-280MWF
SERVICE MANUAL

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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 AMERICA, INC.
618Highway74South
PeachtreeCity,GA 30269
Attn: HOSHIZAKITechnicalSupportDepartment
Phone: [phone]TechnicalService
[phone]
Fax: [phone]
NOTE: Toexpediteassistance,allcorrespondence/communicationMUST includethefollowing
information:
• ModelNumber
• SerialNumber
• Completeanddetailedexplanationoftheproblem
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.

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• 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 ........................................................... 16
[e] CHECKING CONTROLLER BOARD ......................................................... 19
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

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V. REMOVAL AND REPLACEMENT OF COMPONENTS ...........................................33
1. SERVICEFORREFRIGERANTLINES.................................................................33
[a] REFRIGERANT RECOVERY........................................................................33
[b]EVACUATIONANDRECHARGE...................................................................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......................................46
2. CLEANING AND SANITIZING PROCEDURES ..................................................48
[a] CLEANING PROCEDURE ............................................................................49
[b] SANITIZING PROCEDURE...........................................................................50
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.

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2. KM-280MWF (Water-cooled)
* We reserve the right to make changes in specifications and design without prior notice.

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II. GENERAL INFORMATION
1. CONSTRUCTION
[a] KM-280MAF
Spray Tube Water Supply Inlet
Control Switch
Condenser
Bin Control
Thermostat Hot Gas Valve
Expansion Valve Fan Motor,
Condenser
Compressor Drier
Float Switch Control Box
Water Pump

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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
[b] KM-280MWF

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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.

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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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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 prop-
erly, 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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(Control Products HOS-001A Board)
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 ener-
gized 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.

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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.
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.
4. Defrost Timer stops counting.
Defrost cycle is completed, freeze cycle
starts and Line Valve opens.
IMPORTANT
Board never accepts freeze completion signal
within the first 5 minutes in freeze cycle.
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.
4. Defrost Timer stops counting.
Defrost cycle is completed, freeze cycle
starts and Line Valve opens.
IMPORTANT
Board never accepts freeze completion signal
within the first 5 minutes in freeze cycle.
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.
3. Defrost Timer stops counting.
Defrost cycle is completed, freeze cycle
starts and Line Valve opens.
IMPORTANT
Board never accepts freeze completion signal
within the first 5 minutes in freeze cycle.
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:
Switch Nos. 1 and 2:
Used for adjustment of the Defrost Timer.
TheDefrost Timer startscountingwhen the Thermistor readsa 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.
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

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1) Defrost Control
A thermistor (Semiconductor) is used for a defrost control sensor. The resistance var-
ies depending on the Suction Line temperatures. The Thermistor detects the tempera-
ture of the Evaporator outlet to start the Defrost Timer. No adjustment is required. If
necessary, check for resistance between Thermistor leads, and visually check the
Thermistor mounting, located on the Suction Line next to the Evaporator outlet.
Temperature (°F) Resistance (kΩ)
0 14.401
10 10.613
32 6.000
50 3.871
70 2.474
90 1.633
Check a thermistor for resistance by using the following procedures.
(i) Disconnect the connector K3 on the board.
(ii) Remove the Thermistor. See “V. 10. REMOVAL AND REPLACEMENT OF THER-
MISTOR.”
(iii) Immerse the Thermistor sensor portion in a glass containing ice and water for 2 or 3
minutes.
(iv) Check for a resistance between Thermistor leads.
Normal reading is within 3.5 to 7 kΩ. Replace the Thermistor if it exceeds the normal
reading.
2) Defrost Timer
No adjustment is required under normal use, as the Defrost Timer is adjusted to the
suitable position. However, if necessary when all the ice formed on the Evaporator
does not fall into the bin in the harvest cycle, adjust the Defrost Timer to longer setting
by adjusting the Dip Switch (No. 1 & 2) on the Controller Board.
SETTING TIME
Dip Switch Dip Switch
No. 1 No. 2
OFF OFF 60 seconds
ON OFF 90 seconds
OFF ON 120 seconds
ON ON 180 seconds

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3) Drain Timer
The Drain Timer is factory-adjusted, and no adjustment is required.
SETTING TIME
Dip Switch Dip Switch
No. 3 No. 4 T1 T2
OFF OFF 10 seconds 150 seconds
ON OFF 10 seconds 180 seconds
OFF ON 10 seconds 120 seconds
ON ON 20 seconds 180 seconds
T1: Time to drain the Water Tank
T2: Time to restrain defrost completion
4) Drain Counter
CAUTION
Do not adjust the Drain Counter, or the Evaporator may freeze up.
The Drain Counter is factory-adjusted to drain the Water Tank every 10 cycles, and no
adjustment is required. However, where water quality is bad and the icemaker needs a
pump drain more often, the Drain Counter can be adjusted as shown in the table below:
SETTING FREQUENCY
Dip Switch Dip Switch
No. 5 No. 6
OFF OFF every cycle
ON OFF every 2 cycles
OFF ON every 5 cycles
ON ON every 10 cycles

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6) Bin Control
CAUTION
When the ambient temperature is below 45°F, the Bin Control Thermostat
operates to stop the icemaker even if the Ice Storage Bin is empty. When
the Thermostat is set in the prohibited range, the icemaker operates
continuously even if the Ice Storage Bin is filled with ice. Setting in the
prohibited range might cause severe damage to the icemaker resulting in
failure.
No adjustment is required under normal use, as the Bin Control is factory-adjusted.
Adjust it, if necessary, so that the icemaker stops automatically within 10 seconds after
ice contacts the Bin Control Thermostat Bulb.
[e] CHECKING THE CONTROLLER BOARD
1) Visually check the sequence with the icemaker operating.
2) Visually check the Controller Board by using the following procedures.
(i) Adjust the Defrost Timer to minimum position.
Disconnect the Thermistor from the Controller Board.
Connecta 1.5kΩ-3.5kΩresistortothe ConnectorK3(pins#1and #2),andenergize
the unit.
5) Freeze Timer CAUTION
Adjust to proper specification, or the unit may not operate correctly.
Two new dip switches numbered 9 and 10 have been added to the improved “E” board
to better prevent possible freeze ups. These settings come factory set to the default
setting of 60 min. (OFF, OFF). Check the adjustment chart published in the Tech Specs
for proper settings. If the old board does not have these two dip switches, (only 8 in-
stead of 10), leave setting as OFF, OFF.
SETTING TIME
Dip Switch Dip Switch
No. 9 No. 10
OFF OFF 60 min.
ON OFF 70 min.
OFF ON 50 min.
ON ON 60 min.

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(iv) After Step (iii), de-energize the unit and confirm that the Defrost Timer is in the
minimum position. Disconnect the resistor from the Controller Board, and ener-
gize the unit.
After the 1 minute water supply cycle, the defrost cycle starts.
Re-connect a 1.5 kΩ- 3.5 kΩresistor to the Connector K3 (pins #1 and #2) after
the first 2 minutes of the defrost cycle.
The unit should start the freeze cycle after 1 minute ± 5 seconds from the resistor
connection.
3) Check the Controller Board by using test program of the Controller Board.
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, and 4, normal sequence every 5 seconds. S3 should remain in the “OFF” position
for normal operation.
After the 1 minute ± 5 second water supply cycle and the 2 minute ± 10 second defrost
cycle, the unit should start the freeze cycle.
(ii) After the above step (i), disconnect the Float Switch leads from the Controller Board
within the first 5 minutes of the freeze cycle.
The unit should go into the defrost cycle after the first 5 minutes ± 20 seconds of the
freeze cycle.
(iii) Reconnect the Float Switch Connector to the Controller Board. After the first 5
minutes of the freeze cycle, disconnect the Float Switch leads from the Controller
Board.
At this point, the unit should start the defrost cycle.