Only qualied service technicians should install and service the icemaker. To
obtain the name and phone number of your local Hoshizaki Certied Service
Representative, visit www.hoshizaki-europe.com. No service should be undertaken
until the technician has thoroughly read this Service Manual. Failure to service and
maintain the icemaker in accordance with this manual will adversely affect safety,
performance, component life, and warranty coverage and may result in costly water
damage. 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 qualied 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 the appropriate
Hoshizaki Service Office:
UK/Ireland - Hoshizaki UK
TEL : +44 (0)845 456 0585
FAX: +44 (0)132 283 8331
Holland - Hoshizaki Europe
TEL : +31 (0)20 6918499
FAX: +31 (0)20 6918768
Germany/Switzerland/Austria - Hoshizaki Deutschland
TEL : +49 (0)2154 92810
FAX: +49 (0)2154 928128
France - Hoshizaki France
TEL : +33 (0)1 48639380
FAX: +33 (0)1 48639388
Other countries - Hoshizaki Europe
TEL: +31 (0)20 6918499
FAX: +31 (0)20 6918768
Web Site: www.hoshizaki-europe.com
NOTE: To expedite assistance, all correspondence/communication MUST include the
following information:
• Model Number ________________________
• Serial Number ________________________
• Complete and detailed explanation of the problem.
2
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.
CONTENTS
Important Safety Information ................................................................................................. 5
I. Construction and Water/Refrigeration Circuit Diagram ....................................................... 7
A. Construction .................................................................................................................. 7
B. Water/Refrigeration Circuit Diagram .............................................................................. 8
II. Sequence of Operation and Service Diagnosis ................................................................. 9
A. Sequence of Operation Flow Chart ............................................................................... 9
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 qualied 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 specications. 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.
5
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.
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.
6
I. Construction and Water/Refrigeration Circuit Diagram
A. Construction
1. Air-Cooled Models (MAJ-E)
Drain Valve
Cleaning Valve
Water Supply Inlet
Spray Tubes
Evaporator
Inlet Water Valve
Thermostatic
Expansion Valve
Float Switch
Compressor
Water Pump
Control Switch
Stainer
Hot Gas Valve
Condenser
High-Pressure
Switch
Fan Motor
Liquid Line
Valve
Drier
Bin
Control
Control Box
Mode Switch
Model Shown: KM-520MAJ
7
B. Water/Refrigeration Circuit Diagram
1. Air-Cooled Models (MAJ-E)
Hot Gas
Val ve
Condenser
High-Pressure
Switch
Drier
Fan
Liquid Line Valve
Heat
Exchanger
Thermistor
Water Supply
Strainer
Suction Line
Discharge Line
Compressor
Thermostatic Expansion Valve
Spray Tubes
Inlet Water Valve
Water Pump
Drain
Refrigeration Circuit
Water Circuit
Evaporator
Bypass Valve
Drain Valve
Float Switch
Water Tank
8
II. Sequence of Operation and Service Diagnosis
A. Sequence of Operation Flow Chart
1. Operation Flow Chart
cycle
(S4 dip switch 5)
de-energizes for 2 sec.,
then energizes for
10/20 sec.
(S4 dip switch 3 & 4)
FS opens or freeze
FS in control
timer terminates
Comp energized
DV energized
HGV energized
PM de-energizes for 2 sec.,
then energizes for 10/20 sec.
Slush Control
Thermistor temperature
reaches 36°F (2.2°C)
(5.8 kΩ).
PM de-energized for 10 sec.
FM de-energized
LLV de-energized
4. Pump-Out Cycle
• Factory set for every 10th
• Pump motor
• Min. freeze time: 5 min.
3. Freeze Cycle
switch 9 & 10).
• Max. freeze time: freeze timer setting (S4 dip
5-min.
minimum
freeze timer in
Harvest Pump
control
Timer
FS closed
50 sec.
Comp energized
FM energized
PM energized
LLV energized
HGV de-energized
FS check
FS open
Operation Flow Chart
PM energized
WV de-energized
FS closed
Thermistor temperature reaches
Comp energized
HGV energized
48°F (9°C) (3.9 kΩ or less).
Harvest timer starts.
WV energized
Components Energized when the Control Switch is in the "PUMP" Position
When the control switch is in the "PUMP" position power is supplied to the pump motor. Water tank contents then ows over the outside of the
evaporator plate assembly. Note: Water tank contents does not ow inbetween the evaporator plates.
(S4 dip switch 7), whichever is shorter. Do not adjust S4
dip switch 7 out of the factory position.
• WV time: 6 min. or the length of harvest minus 50 sec.
2. Harvest Cycle
1 to 3-min. harvest timer in
control (S4 dip switch 1 & 2)
Thermistor
in control
• Max. harvest time: 20 min.
WV energized
FS open
If FS is open, Comp stops and cycle returns to
1-Min. ll.
then initiates a clean/sanitze program. See the maintenance label on the top cover or the instruction manual for details.
over outside of evaporator plate assembly as the control board power supply has been disconnected. The Clean/Sanitize program cannot initiate in this scenario.
• When the control switch is in the "ON" position and the mode switch is in the "CLEAN" position power is supplied to the control board K9 connector. The control board
Legend:
BC–bin control
Comp–compressor
DV–drain valve
FM–fan motor
FS–oat switch
HGV–hot gas valve
LLV –liquid line valve
PM–pump motor
Components Energized when the Control Switch is in the "ON" or "PUMP" position and the Mode Switch
WV–inlet water valve
• When the control switch is in the "PUMP" position and the mode switch is in the "CLEAN" position, only the pump motor energizes and circulates water tank contents
is in the "CLEAN" Position
Fill Cycle
FS check
1. 1-Minute
Cycle
Steps
Startup
9
2. Shutdown Flow Chart
3. Ice Level Lowered
2. Icemaker Off
Icemaker starts at
"1. 1-Minute Fill Cycle."
All components
de-energized.
To 1. 1-Minute Fill Cycle
BC closed
(BC sensor disengaged)
Green UBC LED on
Yellow "BC OPEN" LED off
Yellow "BC OPEN" LED continues. All
components de-energized.
Shutdown Flow Chart
Control board retains freeze-time correction count data
between bin control restarts.
to 15 sec. into the freeze cycle if
activated at the end of the harvest cycle.
15 sec. before the 5-min. short cycle
protection timer terminates.
Otherwise, at the end of the next harvest
cycle.
BC open (BC sensor engaged)
Green UBC LED off
Yellow "BC OPEN" LED on
BC Operation
Legend:
BC–bin control
1. Bin Full
Shutdown
Shutdown Delay:
and Restart
• Fill Cycle–15 sec. after activation.
• Harvest Cycle–At the end of the harvest cycle, or up
• Freeze Cycle– 15 sec. after activation if activated at least
10
B. Service Diagnosis
WARNING
• The appliance should be diagnosed and repaired only by qualied service
personnel to reduce the risk of death, electric shock, serious injury, or re.
• Risk of electric shock. Control switch in "OFF" position does not de-energize all
loads Use extreme caution and exercise safe electrical practices.
• Moving parts (e.g., fan blade) can crush and cut. Keep hands clear.
• Before servicing the appliance, move the control switch to the "OFF" position and
turn off the power supply.
• CHOKING HAZARD: Ensure all components, fasteners, and thumbscrews are
securely in place after the appliance is serviced. Make sure that none have fallen
into the dispenser unit/ice storage bin.
• Make sure all food zones in the appliance and dispenser unit/ice storage bin are
clean after service.
The diagnostic procedure is a sequence check that allows you to diagnose the electrical
system and components. Before proceeding, check for correct installation, proper voltage
per nameplate, and adequate water supply. Check CB using the steps in "II.C. Control
Board Check." Check dip switch settings to assure that S4 dip switches and S5 dip
switches 1 through 5 are in the factory default position. S4 dip switch 1, 2, 3, 4, and 5 are
cleaning adjustments and the settings are exible. For factory default settings, see "III.C.1.
Default Dip Switch Settings."
Note: • When checking high voltage (230VAC), check electrical outlet power supply and
conrm 13A power supply cord fuse is good.
• Main transformer; The 115VAC neutral (W) for components is provided through
the main transformer. To conrm a good 115VAC neutral (W), check for 60VAC
from white (W) neutral to ground/earth (GND (EARTH)). If 60VAC is present,
main transformer and neutral is good. If 60VAC is not present, check 230VAC
main power supply to the main transformer. If 230VAC is present at the electrical
outlet, check power supply cord fuse and main transformer continuity.
• When checking component high voltage (115VAC), always choose a white (W)
neutral wire to establish a good neutral connection.
• When checking voltage from the CB K1 connector (10 pin connector), pull
CBK1connector out slightly to allow room for multimeter test leads contact.
1) Remove the front panel, then move the control switch to the "OFF" position. Next,
unplug the power supply cord from the electrical outlet. Access the control box and
check that the 115VAC 10A fuse is good.
2) Clear ice from BC sensing area.
11
1. Sequence and Component Diagnosis
3) Power On: Plug the power supply cord back into the electrical outlet, then move the
control switch to the "ON" position and the mode switch to the "ICE" position.
A 5-sec. delay occurs. CB red "POWER OK" LED turns on. If CB yellow "BC
OPEN" LED is on (indicating a full bin), move ice away from BC sensing area or
see "II.D. Bin Control Check and Adjustment."
Note: • CB red "POWER OK" LED remains on unless the 10.5VAC power supply is
interrupted (K2 connector).
• Check CB using the steps in "II.C. Control Board Check" or
BC using steps in "II.D. Bin Control Check and Adjustment."
a) Power On Diagnosis: If CB red "POWER OK" LED is off, conrm 10A fuse is good.
Check for 115VAC at control switch #2 (BK) to neutral (W) then at control switch #1(P)
to neutral (W). If 115VAC is present on #2 (BK) and not on #1(P), replace control
switch. If 115VAC is present on control switch #1 (P), check for 115VAC at HPS (P)
to neutral (W) then HPS (BK) to neutral (W). If115VAC is present at HPS (P) and not
at HPS (BK), HPS is open. See HPS Diagnosis below. If 115VAC is present at HPS
(BK), check for 10.5VAC at CB K2#1 red wire to CB K2 #2 red wire. If 10.5VAC is not
present, check CT continuity. If open, replace CT.
b) HPS Diagnosis: Check that the condenser coil is not clogged or restricted. Let
refrigeration circuit pressures equalize. If HPS does not reset and pressures are
equalized, replace HPS. If pressures are not equalized, reclaim refrigerant and
diagnose refrigeration circuit restriction. Check that there are no restrictions in the
refrigeration circuit.
Harvest Cycle: HGV, strainer, or check valve.
Freeze Cycle: FM, TXV, LLV, strainer, check valve, and drier.
Conrm that the location meets installation requirements:
• The appliance is not intended for outdoor use. Normal operating ambient temperature
should be within 45°F to 100°F (7°C to 38°C).
• Allow 6" (15 cm) clearance at rear, sides, and top for proper air circulation and ease of
maintenance and/or service should they be required.
• The appliance should not be located in a corrosive environment.
4) 1-Min. Fill Cycle – LED 4 is on. WV energizes. After 1 min., CB checks for a closed
FS. If FS is closed, the harvest cycle begins. If harvest cycle begins (Comp and HGV
energize), continue to step 5a. If FS is open, WV remains energized until FS closes (low
water safety protection during initial start up and at the end of each harvest).
Diagnosis: Check that water enters the water tank. If not, check that the water supply
line shut-off valve is open and screens or external lters are clear. Check for 115VAC
at CB K1 #6 (O) to neutral (W). If 115VAC is not present, replace CB. If 115VAC is
present, and WV does not energize, check for 115VAC at WV. If 115VAC is present,
check coil continuity. Ifopen, replace WV. If the water tank lls, but the appliance fails to
start harvest (Comp energized), check for open FS. See "II.E. Float Switch Check and
Cleaning." If FS is closed and CB fails to start the harvest cycle after 1 min., replace CB.
12
5a) Initial Harvest Cycle – LEDs 1, 4, and 2 are on. WV continues. Comp and HGV
energize. CB monitors the warming of the evaporator via the thermistor located on
the suction line. When the thermistor reaches 48°F (9°C), CB reads 3.9 kΩ from the
thermistor and turns harvest termination over to the harvest timer (S4 dip switch 1 &
2and S5 dip switch 4). WV is energized during harvest for a maximum of 6 min. or the
length of harvest minus HPT setting (S4 dip switch 6), whichever is shorter. See step 5b
below.
a) Comp Diagnosis: Check that evaporator is warming. Ifnot, conrm that Comp
energizes. If not, check for 115VAC at CB K1 #9 (Y) to neutral (W). If 115VAC is not
present, check for 115VAC at CB K1 #10 (BK) to neutral (W). If115VAC is present
at #10 (BK) and not at #9 (Y), replace CB. If 115VAC is present, check for 115VAC
at mode switch #2 (Y) to neutral and mode switch #1 (V) to neutral. If 115VAC is
present at #2 (Y) and not at #1 (V), conrm mode switch is in "ICE" position. If in
"ICE" position, check mode switch continuity. If open, replace mode switch. If 115VAC
is present at mode switch #1 (V), check for 115VAC at CR solenoid. If 115V AC is
present, conrm contacts are closed. If not, replace CR. If CR contacts are closed,
check Comp external overload, Comp start and run capacitors, Comp start relay, and
Comp motor winding.
b) HGV Diagnosis: If Comp is energized and evaporator is not warming, check that
HGV energizes and opens. Check for 115VAC at CB K1 #2 (P) to neutral (W).
If115VAC is not present, check for 115VAC at CB K1 #1 (V). If 115VAC is not present,
check wiring for loose connection from CB 10 pin connector pin #1 (V) to mode
switch. If 115VAC is present on #1 (V) and not at #2 (P), replace CB.
If 115VAC is present at #2 (P), check for 115VAC at HGV coil and check HGV coil
continuity. Replace as needed. Note: LED is off when HGV is energized and on when
LLV/FM are energized.
c) LLV Diagnosis: Conrm that LLV is de-energized and closed (not bypassing).
Ifenergized, replace CB. If de-energized and bypassing, replace LLV.
5b) Harvest Pump Time (Harvest Assist) – LEDs 1 and 3 are on. When the thermistor
reaches 48°F (9°C), CB reads 3.9 kΩ from the thermistor and turns harvest termination
over to the harvest timer (S4 dip switch 1 & 2 and S5 dip switch 4).
When WV de-energizes, LED 4 turns off and LED 3 turns on. PM energizes. Comp and
HGV continue.
Diagnosis: Place a thermometer on the suction line next to the thermistor. Has it
warmed to 48°F (9°C) or warmer? Conrm thermistor status. See "II.F. Thermistor
Check." If the thermistor reading is in proper range, dip switch 7 is on, and PM does not
energize before harvest terminates, replace CB. If WV continues, check for 115VAC at
CB K1 #6 (O). If115VAC is present, and LED 4 is off, replace CB. If LED 3is on and PM
is not energized, check for 115VAC at CB K1 #4(R). If115VAC is not present, replace
CB. If 115VAC is present and PM is not energized, check PM capacitor and motor
winding continuity.
13
5c) Initial Harvest Cycle Termination Diagnosis: When the thermistor reaches 48°F
(9°C), CB reads 3.9 kΩ from the thermistor and turns harvest termination over to
the harvest timer (S4 dip switch 1 & 2 and S5 dip switch 4). Check discharge line
temperature. For a thermistor check, see "II.F.Thermistor Check." If 1-min. ll cycle
starts after harvest timer terminates, check that FS is clean and operating properly, see
"II.E. Float Switch Check and Cleaning." If FS is closed, CB proceeds to the next cycle.
Ifnot, replace CB.
Note: The minimum total time allowed by CB for a complete harvest cycle is based on
S5 dip switch 4. Maximum harvest time allowed is 20 min.
NOTICE! S4 dip switch 7 must remain on. Otherwise, PM will not energize during
the last seconds of harvest.
6) Freeze Cycle – LED 1, 2, and 3 are on. Comp and PM continue. FM and LLV energize.
HGV de-energizes. Appliance is held in freeze by a 5-min. short cycle protection
timer. After 5-min. short cycle protection timer terminates and FS opens, freeze cycle
terminates.
Note: PM power supply continues from CB K1 #4 (R) in harvest and in freeze.
Slush Control: When slush control is enabled (S5 dip switch 5 "ON"), PM de-energizes
when thermistor reaches 36°F (2.2°C) (5.8 kΩ) for 10 sec. then, energizes for the
remainder of the freeze cycle.
a) Freeze Cycle Diagnosis: Conrm Comp and PM continue. Conrm that FM and
LLV energize. Next, conrm HGV de-energizes. During the rst 5 min. of freeze,
conrm evaporator is cooling. If not, conrm WV de-energized (not leaking by),
HGV de-energized (not bypassing), LLV and FM energize, TXV operates correctly,
Comp is efficient, and refrigerant charge is correct. See "VIII.A. Specication and
Performance Data Sheets."
b) Comp Diagnosis: If Comp de-energizes once freeze begins, check that appliance
has not shut off on HPS (CB "POWER OK" LED off). If so, check "3)b) HPS
Diagnosis" above. If CB "POWER OK" LED is on, check for 115VAC at CB K1 #9
(Y) to neutral (W). If 115VAC is not present and LED 1 is on, replace CB. If 115VAC
is present, check for 115VAC at CR coil. If 115VAC is present, check CR coil and
contact continuity. Replace as needed. If CR is okay, check Comp external overload,
Comp start and run capacitors, Comp start relay, and Comp motor winding. If Comp
is energized but evaporator is not cooling, check for an inefficient Comp.
See "VIII.A. Specication and Performance Data Sheets."
c) WV and HGV Diagnosis: If WV is energized, check for 115VAC at CB K1 #6 (O)
to neutral (W). If 115VAC is present after PM energizes in harvest cycle, replace
CB. If 115VAC is not present, replace WV (bypassing). If HGV did not de-energize
at the end of harvest, check for 115VAC at CB K1 #2 (P) to neutral (W). If 115VAC
is present and LED 2 is on, replace CB. If 115VAC is not present, replace HGV
(bypassing).
d) PM Diagnosis: Conrm water is owing over evaporator from PM and not WV. If PM
de-energizes once freeze begins, check for 115VAC at CB K1 #4 (R) to neutral (W).
If 115VAC is not present, replace CB. If 115VAC is present and PM is de-energized,
check PM capacitor and motor winding continuity. Except for 10 sec. slush control.
14
e) FM and LLV Diagnosis: If FM or LLV does not energize, check for 115VAC at CB
K1#3 (BK) to neutral (W). If 115VAC is not present and LED 2 is on, check for
115VAC at CB K1 #1(V). If 115VAC is present at #1 (V) and not at #3 (BK), replace
CB. If 115VAC is present and LED 2 is on:
For FM, check capacitor, motor winding, and blade for binding.
For LLV, check coil voltage and continuity.
Note: LED 2 is on for LLV/FM and off for HGV.
f) Refrigerant Pressures and TXV Diagnosis: If evaporator is still not cooling, check
refrigerant pressures. See "VIII.A. Specication and Performance Data Sheets."
Next, check TXV for proper operation. Remove TXV bulb and hold it in your hand,
refrigerant low-side pressure should rise, place TXV bulb in ice water, refrigerant
low-side pressure should drop. A 10 to 15 pound pressure swing between warm and
cold conditions indicate a good TXV. If a 10 to 15 pound swing is not present, replace
TXV.
g) Freeze Termination Diagnosis: After 5 min. in freeze, disconnect CB K5 FS
connector. 15 sec. later appliance should switch out of the freeze cycle (15 second
delay after FS opens before terminating the freeze cycle). If appliance remains in
freeze longer than 15 sec. after FS removed, replace CB. If appliance switches with
FS removed but would previously not switch out of freeze with FS connected (long
freeze - 3 beep alarm), see "II.E. Float Switch Check and Cleaning."
Note: Normal freeze cycle will last 20 to 40 min. depending on model and conditions.
Cycle times and pressures should follow performance data provided in this
manual. See "VIII.A. Specication and Performance Data Sheets."
h) Short Freeze Cycle Diagnosis: Conrm water tank lls and overows during 1 min.
ll and harvest cycles. If not, check water supply lters, shut-off valve, WV screen.
Ifwater tank empties before 5 min. timer terminates and freeze cycle is short, check
that DV is not leaking by (water owing down the drain). If DV is leaking by, remove
and clean DV, replace if necessary. If water tank is full, see "II.E. Float Switch Check
and Cleaning." for erratic operating FS.
15
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