INTRODUCTION
MDT6N90
To the owner or user: The service manual you are
reading is intended to provide you, and the
maintenance or service technician with the
information needed to install, start up, clean,
maintain, and service this ice maker-dispenser.
The MDT6 is a combination nugget ice maker and
countertop dispenser. A water station is standard.
Table of Contents
FOR THE INSTALLER: Specifications ······························ Page 2
FOR THE INSTALLER ······································ Page 3
FOR THE PLUMBER ······································· Page 4
FOR THE ELECTRICIAN ····································· Page 5
FOR THE INSTALLER: Final Check List ····························· Page 6
INITIAL START UP ········································ Page 7
COMPONENT DESCRIPTION ·································· Page 8
COMPONENT DESCRIPTION ·································· Page 9
CONTROL BOX ········································· Page 10
ELECTRICAL SEQUENCE ···································· Page 11
OPERATION: Water ······································· Page 12
OPERATION: Refrigeration ···································· Page 13
OPERATION: Ice Vending ···································· Page 14
DISPENSE AREA SANITATION ································· Page 15
CLEANING and SANITIZING ··································· Page 16
SENSOR MAINTENANCE ···································· Page 17
BEARING MAINTENANCE ···································· Page 18
AUGER MAINTENANCE ····································· Page 19
SERVICE DIAGNOSIS ······································ Page 20
CONTROL SYSTEM DIAGNOSTICS ······························ Page 21
REMOVAL AND REPLACEMENT ································ Page 22
REMOVAL AND REPLACEMENT: Bearing And Breaker ···················· Page 23
REMOVAL AND REPLACEMENT ································ Page 24
REMOVAL AND REPLACEMENT: Water Seal ·························· Page 25
REMOVAL AND REPLACEMENT ································ Page 26
TO REMOVE AND REPAIR THE GEARMOTOR ASSEMBLY ·················· Page 27
REFRIGERATION SERVICE ··································· Page 28
The ice making section is equipped with the
following features: electronic controls for bin level
and low water; thermostatic expansion valve; front
service for most components; and R-404A
refrigerant. The ice dispensing section is a
seamless plastic storage bin, with a stainless steel
ice agitator at the bottom to sweep the ice into the
dispensing chute.
This manual was printed on recycled paper.
Keep it for future reference.
Note this symbol when it appears.
It marks a possible hazard.
May 2001
Page 1
MDT6N90
FOR THE INSTALLER: Specifications
This ice maker-dispenser is designed to be
mounted on a machine stand, or a countertop.
Before beginning the installation, check that all the
materials and kits required are available at the
installation location.
Scotsman Ice Systems are designed and
manufactured with the highest regard for safety
and performance. They meet or exceed the
standards of U.L., N.S.F., and C.U. L.
3/8" FPT
Cond. Water
Inlet
(W/C)
1/2" FPT
Cond. Drain
(W/C)
3/4 FPT
Drain
Scotsman assumes no liability or responsibility of
any kind for products manufactured by Scotsman
that have been altered in any way, including the
use of any parts and/or other components not
specifically approved by Scotsman.
Scotsman reserves the right to make design
changes and/or improvements at any time.
Specifications and designs are subject to change
without notice.
BACK VIEW
Water Limitations:
An ice machine is a food
manufacturing plant; it takes in
a raw material, water, and
turns it into a food product,
ice. The purity of the water is
very important in obtaining
pure ice and in maximizing
product life.
General recommendations
Electrical Junction
Box
3/8" Flare
Water Inlet
are:
1. Filter the water used to
produce ice.
2. Check with a water
treatment specialist for a water
test, and any
6.63"
12.5"
4.63"
recommendations regarding
filters and treatment.
.75"
3/4" FPT
Drain
Model Number Model
Series
3.84"
5.59"
17.59"
Dimensions
(w/o stand)
H"xW"xD"
2.63"
Condenser
Type
Refrigerant
7.93"
Charge
(R-404A)
Basic
Electrical
Minimum
Circuit
Ampacity*
MDT6N90A-1 J 45.74 x 35.18 x 29.26 Air 32 115/60/1 18.1 25
MDT6N90W-1 J same Water 19 115/60/1 16.5 20
MDT6N90AS-1 A or B same Air 32 115/60/1 18.1 25
MDT6N90WS-1 A same Water 22 same 16.5 20
MDT6N90WS-1 B same Water 19 same 16.5 20
*Minimum circuit ampacity is used to determine wire size and type per National Electric Code.
Options: Machine stand DMS31.
August 2010
Page 2
Max.
Fuse
Size
FOR THE INSTALLER
MDT6N90
Location
This ice system is designed to be installed indoors,
in a controlled environment.
Minimum Maximum
Air Temp 50
Water Temp 40
0
F. 1000F.
0
F. 1000F.
Water Pressure 20 psi 80 psi
Voltage 104 126
Operating the machine outside of the above
limitations, or outdoors, is potentially damaging to
the machine; also it is misuse of the machine
which may void the warranty.
Service Limitations
Do not install in a location where the top of the
machine is within 6" of a fixed ceiling. Air cooled
models require a minimum of 6 inches to the left
and right of the machine for air circulation. It is
important that the machine be installed in a
location where it has enough space above and
behind it for service.
After uncrating and inspection, the unit is ready for
installation.
Machine Stand Installation
Tip the stand on its back and install the legs, return
the stand to the upright position. Adjust leg levelers
so that the stand does not “rock”.
Counter Top or Machine Stand Installation
The base of the icemaker-dispenser must be
sealed to the object it rests upon. Food grade
silastic sealant such as Scotsman part number
19-0529-01 is recommended.
Place a bead of the sealant on the machine stand
or counter top to match the outside edge of the
cabinet base and sink.
The icemaker-dispenser is heavy: use of a
mechanical hoist is recommended to lift it to the
height required to install it.
The DMS machine stand has holes in the top that
match up with threaded holes in the base of the
machine. Secure the machine stand to the base
with 4 5/16" bolts.
In both counter top and machine stand
installations, wipe off and neatly smooth any
excess sealant. Level the machine stand and
cabinet.
Unpack and install the sink brackets. Fit the sink
assembly onto the two sink brackets, and press
onto the bead of sealant. Wipe off and neatly
smooth any excess sealant from under the sink
edge. Connect the sink drain to the dispenser drain
system.
Airflow
SEAL
ICEMAKER-
DISPENSER TO
THE COUNTER
TOP OR
MACHINE STAND
May 2001
Page 3
MDT6N90
FOR THE PLUMBER
CONFORM TO ALL APPLICABLE CODES
Water Inlet
Air Cooled Models: Connect a clean, potable
and cold water supply to the
back of the cabinet. Install a hand valve near the
machine to control the water supply. Use
copper tubing.
Water Treatment: In most areas, a water filter of
some type will be useful. In areas where the water
is highly concentrated with minerals the water
should be tested by a water treatment specialist,
and the recommendations of the specialist
regarding filtration and/or treatment should be
followed.
Water Cooled Models: Connect a separate
O.D. copper line, with a separate hand valve to
control it, to the
3
” FPT condenser inlet at the
8
back of the cabinet. The water pressure to all lines
must always be above 20 psig, and below 120
psig.
3
” male flare at the
8
3
8
” O.D.
3
”
8
INLET WATER
Drains
Air Cooled Models: Connect a drain tube to the
one ¾” FPT drain fitting (plastic) at the back of the
cabinet, the drain line is of the gravity type, and ¼
inch per foot fall is an acceptable pitch for the
drain tubing. There should be a vent at the
highest point of the drain line, and the ideal drain
receptacle would be a trapped and vented floor
drain. Use only ¾” rigid tubing.
WATER COOLED
CONDENSER
WATER INLET
CONDENSER
DRAIN
Water Cooled Models: In addition to the above
mentioned drain, a separate condenser drain line
must be installed. Connect it to the ½ " condenser
drain connection at the back of the cabinet.
VENTED
DRAIN
OPTIONAL
WATER
FILTER
SHUT OFF VALVE
FLOOR DRAIN
May 2001
Page 4
FOR THE ELECTRICIAN
CONFORM TO ALL APPLICABLE CODES
Connect the electrical power supply for the unit to
the wires in the junction box at the rear of the
machine.
Check the nameplate (located on the back panel)
for the voltage requirements, and for the minimum
circuit ampacity. The machine requires a solid
chassis to earth ground wire.
The ice maker should be connected to its own
electrical circuit so it would be individually fused.
Voltage variation must remain within design
limitations, even under starting conditions.
All external wiring must conform to national,
state, and local electrical codes. The use of a
licensed electrician is required to
perform the electrical installation.
MDT6N90
POWER SUPPLY
ELECTRICAL
CONNECTION
May 2001
Page 5
MDT6N90
FOR THE INSTALLER: Final Check List
1. Is the icemaker-dispenser installed
indoors, in a location where the air and
water temperatures are controlled, and
where they do not go beyond design
limitations?
2. is there an electrical service
disconnect within sight of the installed
machine? Is the machine on a separate
circuit? Has the voltage been checked
and compared to nameplate
requirements?
3. Have all of the plumbing connections
been made and checked for leaks?
4. Has the machine been leveled?
5. Is there a minimum of 6 inches of
clearance at the left and right sides of an
air cooled machine?
ELECTRICAL?
LEVELED?
6. Is there a minimum of 6 inches of
clearance at the top and back of the
machine for service and utility
connections?
7. Is there a water shut off valve installed
near the machine?
8. Have all of the shipping blocks been
removed?
WATER
INLET?
DRAINS?
May 2001
Page 6
INITIAL START UP
Pre Start Inspection
1. Remove the two front panels.
2. Check that all shipping blocks have been
removed.
3. Remove any and all packing tape (check inside
the storage bin).
4. Inspect the interior of the machine for loose
screws or wires. Check that no refrigerant lines are
rubbing each other. Check that the fan blade on air
cooled models turns freely.
5. Check that the machine is installed correctly
according to the final check list.
Start Up
1. Go through the pre start inspection.
2. Open the water hand valve, observe that water
enters the water reservoir, fills the tube from the
reservoir to the evaporator and then shuts off.
Check for leaks.
3. Switch the mode switch to ON. The auger drive
motor and compressor start, beginning the ice
making process.
4. On air cooled models, warm air will begin to flow
from the condenser. Water cooled models will
begin to discharge warm water down the drain.
MDT6N90
7. Check ice dispensing by pushing in on the glass
filler lever. Ice dispenses are portion controlled; by
turning a knob, the length of time the unit
dispenses when the glass filler lever is pushed
(and the amount of ice dispensed) is adjusted.
8. Switch off the icemaker-dispenser, remove the
top panel and the top of the ice storage bin.
Sanitize the interior of the ice storage bin with a
locally approved sanitizer. A possible sanitizer is a
mixture of 1 ounce of household bleach to 2
gallons of water. Wash the interior of the bin with
the sanitizing solution. Replace all covers and
panels. Switch the icemaker-dispenser back on.
5. The unit should soon be making ice. If desired,
the low side pressure may be checked: it should be
38 PSIG + or - 4 PSIG.
The air cooled discharge pressure will depend
upon air and water temperatures, but should be
between 200 PSIG and 300 PSIG.
Water cooled discharge pressure should be about
245 PSIG. If needed, adjust the water regulating
valve.
The above numbers are for new, clean machines.
Field values may be somewhat higher or lower.
6. There are no adjustments to make, so replace
the panels.
May 2001
9. Give the owner/user the service manual, instruct
him/her in the operation and maintenance
requirements of the unit. Make sure they know who
to call for service.
10. Fill out the Customer Evaluation and warranty
Registration form, and mail it in to Scotsman.
Page 7
MDT6N90
COMPONENT DESCRIPTION
ICE LEVEL SENSOR
EVAPORATOR
DRAIN
TUBE
RESERVOIR
WATER
LEVEL
SENSOR
ICE STORAGE BIN
CONTROL BOX
CONDENSER
HI
PRESSURE
CUT OUT
Control Box: Contains the electrical controls that
operate the machine.
High Pressure Cut Out Switch: An automatic
reset switch sensing the high side refrigeration
pressure. It is set to shut the machine off if the
discharge pressure should ever exceed 450 psig.
Evaporator: A vertical stainless steel tube,
refrigerated, and water filled. In it there is a
stainless steel auger.
Reservoir: Float operated, it maintains the water
level in the evaporator at a constant level, it also
contains the water level sensor.
Water Level Sensor: Senses if there is water in
the reservoir to make ice out of. Will shut the
machine off it there is none.
Ice Level Sensor: An electronic “eye”, it senses
the presence of ice in the bottom of the ice
discharge chute. Operates to turn the ice machine
on and off automatically as the level of ice in the
bin changes.
Drain Tube: When uncapped and lowered, drains
the evaporator.
Condenser: Air or water cooled, where the heat
removed in ice making is discharged.
Ice Storage Bin Assembly: A plastic lined,
insulated cylinder that receives, stores and
dispenses the ice. Fresh ice enters at the top, and
when the bin is full enough the ice will be between
the ice level sensors, and the icemaking will stop.
Ice is dispensed through a chute at the bottom
front when the agitator assembly sweeps the ice
through the chute.
May 2001
Page 8
COMPONENT DESCRIPTION
MDT6N90
Evaporator: A refrigerated vertical tube filled with
water and containing a water seal and auger.
Auger: A solid stainless steel double spiral auger,
it pushes the ice crystals up to the top of the
evaporator.
Water Seal: A two part “face” seal, the top half
rotating with the auger, the bottom half stationary,
the sealing action being where the two seal “faces”
meet.
Ice Sweep: A plastic cap with “fingers”. It revolves
with the auger to “sweep” the ice into the ice chute.
Breaker: Where the ice is compressed and much
of the extra water is squeezed out of it before it is
discharged into the bin.
ICE CHUTE
Motor: A split phase motor that drives the gear
reducer.
Thrust Bearing: As the ice is pushed up the
evaporator, the auger is thrust down, and pressure
from the auger thrust is taken up by this bearing.
ICE SWEEP
BEARING
BREAKER
AUGER
WATER SEAL
WATER INLET
GEAR MOTOR
EVAPORATOR
May 2001
Page 9
MDT6N90
CONTROL BOX
Circuit Board:
The circuit board receives input signals from
several sensors and translates them to control the
electrical power supply to the various loads.
The sensors include:
Touch Free ice or water.
·
Ice level in the bin.
·
Water level in the reservoir.
·
The loads include:
Compressor contactor
·
Fan motor
·
Bin drive motor
·
Auger drive motor
·
Water solenoid.
·
In addition, a “Clean” switch is
available to temporarily disable the
Touch-Free sensors for cleaning of the
splash panel.
On/Off Switch: Manual control for the
machine.
Contactor: A definite purpose
contactor connecting the compressor
to the power supply.
Potential Relay: The compressor
start relay.
May 2001
Page 10
Touch Free Control Board
ELECTRICAL SEQUENCE
MDT6N90
Refer the wiring diagram as needed.
The “Power” light on the board glows whenever
there is power to the machine (and the master
switch is ON).
If the machine is switched off at the master switch,
but is otherwise ready to go, switching the master
switch to ON does the following:
The bin empty and power lights on the circuit
·
board glow.
There is a 15 second delay
·
If there is enough water in the reservoir, the
·
circuit board will allow the machine to start up.
Start up consists of:
The compressor contactor coil receives power
·
from the circuit board.
The contactor is energized, connecting power to
·
the compressor, and the compressor starts.
The auger motor receives power from the circuit
·
board and starts.
As ice goes past the ice level sensors, the bin
·
empty light will stay on and the machine will
continue to run, unless the ice stays between
the sensors for more than 15 seconds (bin full).
At that point, the bin empty light goes out, and
the machine shuts down.
Other reasons for shut down:
·
Low water level (as sensed by the thermistor in
the reservoir).
Shut Down consists of:
·
The compressor contactor opens
After a 6 minute delay, If the ice level sensor is
clear (bin empty) for more than 15 seconds, the
machine will start up again.
Another purpose of the circuit board is to turn the
machine off if there is not enough water in the
machine.
When the water level in the reservoir falls
·
below the tip of the water level sensor, the
machine will “shut down”
After a 6 minute delay, if the water refills the
·
reservoir, the machine will start up again.
Separate from the circuit board:
If the high pressure control (cut out switch)
·
opens, the compressor will stop immediately
(through the contactor). It will automatically
reset when the discharge pressure drops below
350 PSIG.
The master switch is the manual control for the
·
complete machine, but it is not a service
disconnect.
Ice Vending
When a user places a container in front of the
·
Touch Free ice sensor and below the ice
delivery chute, the circuit board connects power
to the bin drive motor and ice is dispensed for
as long as the container is present. If the user
does not remove the container, ice will be
dispensed for 60 seconds and then stop.
·
The compressor stops
·
The auger motor is run by the circuit board for 2
more minutes, clearing out ice in the evaporator,
and then
·
The auger motor no longer receives power from
the circuit board, and the auger motor stops.
May 2001
Page 11
MDT6N90
OPERATION: Water
Water enters the machine through the 3/8" male
flare at the rear of the cabinet, goes to the water
reservoir which it enters through the float valve.
The water then goes out the bottom of the
reservoir tank to the bottom of the evaporator.
Reservoir overflow, evaporator condensation and
water in the sink are all routed to the drain. Water
cooled models have a separate water circuit for the
cooling water: it enters the fitting at the rear, goes
to the water regulating valve, then to the water
cooled condenser and down the drain.
The water dispensing station adds an additional
water circuit. When the water station sensor
detects a container in front of it, the control board
closes a circuit to an electric water valve and water
is dispensed.
Note: The correct water level is determined when
the machine is operating. Check the water level
and compare it to the line molded into the side of
the reservoir. The water level should be between
" above and " below the line.
If needed, adjust the water level by bending the
float arm.
WATER LEVEL
RESERVOIR
RESERVOIR
OVERFLOW DRAIN
WATER
INLET
BIN DRAIN
SINK DRAIN
WATER VALVE
WATER SCHEMATIC
May 2001
Page 12
OPERATION: Refrigeration
MDT6N90
Beginning at the compressor, the refrigerant is
compressed into a high temperature gas. The
discharge line directs this gas to the condenser. At
the condenser (air or water cooled) the gas is
cooled by either air or water and it then condenses
into a liquid. This high pressure liquid then goes
through the liquid line to the expansion valve.
The thermostatic expansion valve meters liquid
refrigerant into the evaporator, the volume of liquid
refrigerant depending upon the temperature of the
evaporator; warmer evaporators get more
refrigerant and colder evaporators get less.
REFRIGERATION SCHEMATIC
(AIR COOLED SHOWN)
At the evaporator, the refrigerant enters an area of
relatively low pressure, where it can easily “boil off”
or evaporate. As it evaporates, it absorbs heat
from the evaporator and whatever is in contact with
it (such as the water inside it). After the evaporator,
the refrigerant, now a low pressure vapor, goes
through the suction line back to compressor, where
the cycle is repeated.
SUCTION LINE
THERMOSTATIC
EXPANSION VALVE
LIQUID LINE
CONDENSER
FAN MOTOR
DISCHARGE
LINE
EVAPORATOR
COMPRESSOR
May 2001
Page 13
MDT6N90
OPERATION: Ice Vending
When the ice dispensing sensor detects a
container in front of it, the control board connects
an electrical circuit to the ice chute door solenoid
causing the ice chute door to open. At the same
time power is connected to the agitator drive
motor.
Dispensing takes place when the agitator sweeps
the ice through the ice dispensing chute: ice will
continue to discharge out this chute as long as the
agitator is turning. It stops when the agitator stops.
ICE DISCHARGE CHUTE
DOOR
SOLENOID
STORAGE BIN
ICE CHUTE
DOOR
ICE CHUTE
AGITATOR
AGITATOR
DRIVE MOTOR
TOUCH FREE
SENSOR
SINK
May 2001
Page 14
DISPENSE AREA SANITATION
The dispense area; spouts, sink, grill and splash
panel will need periodic cleaning and maintenance.
1. The ice chute may be pulled down to remove it
from the ice dispenser. Wash and sanitize it.
2. The sink grill may be removed for washing and
sanitizing.
3. The sink should be flushed with hot water and
wiped clean with sanitizer.
4. The splash panel requires special attention to
clean it.
Push and release the Splash Panel Cleaning
·
switch located to the left of the water spout. This
disables the Touch Free sensors so the splash
panel may be cleaned without vending ice
and/or water.
Wash the splash panel and wipe with with
·
sanitizer.
Re-push the clean switch or allow 2 minutes to
pass for the Touch Free system to reset.
MDT6N90
May 2001
Page 15
MDT6N90
CLEANING and SANITIZING
It is the USER’S RESPONSIBILITY to see that the unit is properly maintained. It is always preferable, and
less costly in the long run, to avoid possible down time by keeping it clean; adjusting it as needed; and by
replacing worn parts before they can cause failure. The following is a list of recommended maintenance
that will help keep the machine running with a minimum of problems.
Cleaning should be scheduled at a minimum of twice per year.
Sanitizing of the ice storage bin should be scheduled for a minimum of 4 times a year.
Electrical power will be ON when doing in place
cleaning.
ICEMAKING SYSTEM: In place cleaning
1. Check and clean any water treatment devices, if
any are installed.
2. Remove screws and remove the upper front
panel.
3. Move the ON-OFF switch to OFF.
4. Remove the cover to the ice storage bin, and
remove the ice.
5. Remove the cover to the water reservoir and
block the float up.
6. Drain the water reservoir and freezer assembly
using the drain tube attached to the freezer water
inlet. Return the drain tube to its normal upright
position and replace the end cap.
7. Prepare the cleaning solution: Mix eight ounces
of Scotsman Ice Machine Cleaner with three quarts
of hot water. The water should be between 90-115
degrees F.
Scotsman Ice Machine
Cleaner contains acids.
These compounds may
cause burns. If swallowed,
DO NOT induce vomiting.
Give large amounts of
water or milk. Call
Physician immediately. In
case of external contact,
flush with water. Keep out
of the reach of children.
10. After all of the cleaning solution has been
added to the reservoir, and the reservoir is nearly
empty, switch the master switch to OFF.
11. After draining the reservoir, as in step 6, wash
and rinse the water reservoir.
To Sanitize:
Repeat steps 8-11, except substitute sanitizer
solution for the cleaning solution.
A possible sanitizer solution may be made by
mixing 1 ounce of household bleach and 2 gallons
of warm (95
12. Remove the block from the float in the water
reservoir.
13. Switch the master switch to ON
14. Continue ice making for at least 15 minutes, to
flush out any cleaning solution. Check ice for acid
taste - continue icemaking until ice tastes sweet.
DO NOT USE any ice produced from the
cleaning solution.
Be sure no ice remains in the bin.
15. Remove all ice from the storage bin.
16. Add warm water to the ice storage bin and
thoroughly wash and rinse all surfaces within the
bin.
17. Sanitize the bin interior, cover, door and
agitator with an approved sanitizer using the
directions for that sanitizer.
18. Replace the ice storage bin cover, and the front
panel.
o
F. - 115oF.) potable water.
8. Slowly pour the cleaning solution into the water
reservoir until it is full. Wait 15 minutes, then
switch the master switch to ON.
9. As the ice maker begins to use water from the
reservoir, continue to add more cleaning solution to
maintain a full reservoir.
May 2001
Page 16
SENSOR MAINTENANCE
MDT6N90
1. The ice machine senses water level by a probe
located in the water reservoir. At least twice a year,
the probe should be removed from the reservoir,
and the tip wiped clean of mineral build-up.
SLIDE SENSORS
UP TO REMOVE
2. The bin control uses devices that sense light,
therefore they must be kept clean enough so that
they can “see”. At least twice a year, remove the
bin control sensors from the ice chute, and wipe
them clean.
May 2001
Page 17
Clean the Probe's Tip with ice
machine cleaner and a clean,
soft cloth.
MDT6N90
BEARING MAINTENANCE
The bearing in the breaker should also be checked
at least two times per year.
A. Check the bearing by:
removing the ice chute cover
·
Ice Sweep
unscrewing the ice sweep
·
removing the water shed
·
Breaker
Cover
unscrewing the breaker cover.
·
Auger Stud
Cap Screw
unscrewing the auger stud
·
Inspect the bearing. There should be plenty of
grease in sight. If grease is needed the bearing
and breaker should be removed to check the
action of the bearing. It should rotate smoothly.
To remove the breaker remove the lower ice chute
then take out all four allen head cap screws and
pull the breaker off the auger and evaporator.
If the bearing only needs grease, inject grease into
the bearing using Scotsman grease needle pn
02-3559-01 and Scotsman bearing grease
cartridge, pn A36808-001. Be sure to inject grease
evenly and thoroughly.
See Removal and Replacement section to replace
bearing or seals.
Off
Reverse to reassemble.
May 2001
Page 18
Bearing
Needle, pn
02-3559-01
AUGER MAINTENANCE
In some areas, the water supply to the ice maker
will contain a high concentration of minerals, and
that will result in an evaporator and auger
becoming coated with these minerals, requiring a
more frequent removal than twice per year. If in
doubt about the condition of the evaporator and
auger, the auger can be removed so the parts can
be inspected.
Note: Water filters can filter out suspended solids,
but not dissolved solids. “Soft” water may not be
the complete answer. Check with a water
treatment specialist regarding water treatment.
For more information on removal of these
parts, see REMOVAL AND REPLACEMENT.
Moving Parts Hazard.
Disconnect electrical
power to the icemaker dispenser before
beginning.
MDT6N90
BREAKER AND
AUGER ASSEMBLY
Disconnect electrical power, and shut off the
water supply.
Use care when removing the auger, it has
sharp edges.
1. To remove the auger, remove the front and top
panels.
2. Drain evaporator using drain hose.
3. Remove bail clamp from over ice chute cover
and remove cover.
4. Unscrew and remove ice sweep.
5. Remove ice chute from evaporator.
6. Remove 4 allen screws holding breaker to
evaporator.
7. Pull up to remove auger.
After the auger has been removed, allow the auger
to dry: if the auger is not bright and shiny, it must
be cleaned.
Clean the auger and evaporator as required. DO
NOT HONE THE EVAPORATOR.
8. Replace the water seal.
9. Reverse to reassemble.
May 2001
Page 19
MDT6N90
SERVICE DIAGNOSIS
Symptom Possible Cause Probable Correction
No ice is made, nothing operates Unit off due to no power Restore Power
Unit off due to master switch in
OFF position.
Unit off due to low water level. Check water supply, filter, float
Unit off due to ice level sensors
(photo-electric eyes) blocked.
Unit off due to scale on water level
sensor.
Unit off due to high pressure
control open.
Auger motor hums but does not
turn.
No power to circuit board. Check harness
Circuit Board gear motor relay will
not close
Water level or ice level sensor
failed.
No ice, auger motor is turning Compressor contactor coil is open Check/replace contactor
Compressor will not start Check start capacitor.
Circuit board compressor relay will
not close.
Unit makes ice, but very slowly. High discharge pressure because
of a dirty condenser
Low capacity because the auger
and evaporator are coated with
mineral scale
Low suction pressure due to low
refrigerant charge
Switch master switch to ON.
valve. Correct water supply.
Check/clean ice level sensors.
Clean water level sensor.
Check for water interruption (water
cooled) or fan motor failure (air
cooled).
Auger can’t turn.
HI pressure cut out open
Check, replace board
Check, replace sensor
Check start relay
Check compressor windings
Check, replace board
Clean the condenser.
Clean the water system
Locate leak. Recover refrigerant,
repair leak, replace dryer,
evacuate and weigh in the
nameplate charge
May 2001
Page 20
CONTROL SYSTEM DIAGNOSTICS
The control system consists of:
Control Board
·
Water Sensor
·
Ice Sensors
·
Vending Sensors
·
MDT6N90
1, Power Light
2, Bin Empty
Light
3, Delay Timer
Light
4, No Water
Light
Explanation of Indicator Light Position On
Board
On at all times when the master switch is ON and machine is
connected to electrical power.
On when ice level is low (unit making ice). 2 Bin Empty,
Normal 6 minute off/delay start. To prevent short cycling, the
machine will not restart after any shut off (except power to the
board) until 6 minutes have passed.
On when water level is low in the reservoir. 4 No Water,
1 Power,
3 Off Timer,
Name and Meaning of
Light or Reset
ON = Normal
ON = Needs Ice
ON = Unit cycling off
ON = Trouble
May 2001
Page 21
MDT6N90
REMOVAL AND REPLACEMENT
WATER RESERVOIR
1. Shut off the water supply to the icemaker.
2. Remove front panel and reservoir cover.
3. To remove float only, pry the mounting flanges
apart enough to lift one float pivot pin out of the
flange hole, and pull float up and out of the
reservoir.
4. To remove reservoir, disconnect water inlet
compression fitting at reservoir inlet.
5. Remove drain hose from reservoir.
6. Remove evaporator inlet hose from reservoir.
7. Remove water level sensor probe.
8. Remove mounting screws from reservoir
bracket, and remove reservoir from icemaker.
9. Reverse to reassemble.
FLOAT
ASSEMBLY
Water
Sensor
LOCKING
TABS
BIN CONTROLS (Ice Level Sensors)
1. Disconnect electrical power.
2. Remove front panel.
3. Remove control box cover.
4. Locate bin top, in front of and behind it are two
rubber bin control grommets.
5. Pull each bin control out, and in the control box,
disconnect the electrical leads connecting the bin
control to the circuit board.
6. Reverse to reassemble, be certain that the bin
controls are aligned so that the ice level sensors
are visible (centered) through the holes in the ice
chute.
May 2001
Page 22
REMOVAL AND REPLACEMENT: Bearing And Breaker
MDT6N90
Note: Removal of the auger, water seal, evaporator
and gearmotor must begin at the top of the
assembly.
To Remove the Breaker Bearing Assembly:
Moving Parts Hazard.
Disconnect electrical
power to the icemaker dispenser before
beginning.
1. Remove panels and disconnect electrical power.
2. Unscrew three studs and remove ice chute
cover.
3. Unscrew and remove ice sweep.
4. Lift up and remove ice chute.
5. The breaker may be removed from the auger
and evaporator without disturbing the auger.
a. Unscrew breaker cover from breaker (left hand
threads)
b. Unscrew auger stud from top of auger.
c. Unscrew 4 allen head cap screws holding
breaker to evaporator.
ICE SWEEP
STEP 5-A STEP 5-B STEPS 5-C
d. Lift up, and remove breaker/bearing assembly
from auger & evaporator.
6. Service the bearing. Check for rust, rough spots
and damage.
a. The bearing is pressed into the breaker, to
remove the bearing and replace it an arbor press is
needed.
b. Replace lower seals before installing new
bearing in breaker.
Note: seals must be pressed in with a tool pushing
against the outer edge only, they will not install by
hand.
Replace parts as required. Re-grease bearing with
Scotsman part no. A36808-001 bearing grease.
Replace top seal, and check the o-rings, replace if
cut or torn.
7. Reverse to reassemble: specific tools and
materials are required to install properly.
a. Add food grade grease such as Scotsman part
number 19-0569-01 to the seal area before
installing on the auger.
b. Check the seal to shaft areas for cuts, or rough
spots: none are permitted.
BEARING
AND 6
May 2001
Page 23
BREAKER
MDT6N90
REMOVAL AND REPLACEMENT
To Remove the Auger:
Turn off the water to the machine, and unclip the
evaporator drain hose, pull it down and drain the
evaporator into the bin or a container.
Moving Parts Hazard.
Disconnect electrical
power to the icemaker dispenser before
beginning.
1. The top panel must be removed.
2. Remove ice chute cover.
3. Unscrew ice sweep.
4. Remove ice chute body.
5. The auger and breaker/bearing may now be
removed as an assembly.
BREAKER/
BEARING/
AUGER
ASSEMBLY
SHARP EDGES!
e. If the auger is stuck use a slide hammer type
puller to pull on the auger at the threaded hole.
The size of that hole is 5/8"-18.
Inspect the auger, the critical areas of the auger
are:
1. The auger body. It should be clean and
shining. Sometimes an auger will appear clean
when wet, but after it is dry it will be seen to be
stained. Scrub the auger with ice machine cleaner
and hot water.
Ice machine cleaner is an acid. Handle it with
extreme care, keep out of the reach of children.
2. The water seal area. Because the auger has
been removed, the water seal will have to be
replaced. Remove the water seal top half from the
auger, and inspect the auger for minerals clean as
required.
SLIDE HAMMER
PULLER
a. Unscrew 4 allen head cap screws holding
breaker to evaporator.
b. Lift up on breaker and remove auger from
evaporator.
Note: If the auger is stuck, the breaker must be
removed from the auger.
The breaker may be removed from the auger and
evaporator without disturbing the auger.
a. Unscrew breaker cover from breaker (left hand
threads)
b. Unscrew auger stud from top of auger.
c. Unscrew 4 allen head cap screws holding
breaker to evaporator.
d. Lift up & remove breaker from evaporator.
May 2001
THREAD INTO
AUGER
Page 24
REMOVAL AND REPLACEMENT: Water Seal
MDT6N90
To Remove the Water Seal:
(Assuming all steps to remove the auger have
been performed.)
1. The gearmotor/evaporator assembly will have to
be exposed. (See illustration - next page)
2. Remove the 4 hex head cap screws holding the
evaporator to the gearmotor assembly. Lift the
evaporator up and off of the gearmotor.
3. Remove the snap ring or wire retainer from the
grove under the water seal.
4. Pull or drive out the lower half of the water seal.
To Replace the Water Seal:
1. Lubricate the water seal with water, and push
the water seal into the bottom of the evaporator
slightly past the grove for the snap ring.
5. Carefully push the water seal (rubber side
against the auger shoulder and the silastic
sealant.)
Do not get any sealant onto the face of the seal.
6. Allow the auger and seal to air dry until the
sealant is dry on the surface.
7. If the original water seal was leaking, it would
be a good idea to inspect the interior of the
gearmotor.
WATER SEAL
RETAINING RING
2. Replace the snap ring and pull the water seal
down against it.
3. The part of the water seal that rotates with the
auger must also be replaced. Remove the old part
from the auger and clean the mounting area.
4. Place a small bead of food grade silastic sealant
(such as 732 RTV or Scotsman part number
19-0529-01) on the area of the auger where the
water seal is to be mounted.
May 2001
FOOD GRADE
SEALANT HERE
Page 25
MDT6N90
REMOVAL AND REPLACEMENT
To Replace the Evaporator:
(Assuming all the steps for removal of the thrust
bearing, breaker, auger, and water seal have been
performed.)
1. Recover the refrigerant from the ice maker.
2. Unsweat the refrigerant connections:
a) At the thermostatic expansion valve outlet.
Heat sink the TXV body when unsweating or
resweating the adjacent tubing.
b) At the suction line at the joint about 3" from the
evaporator.
3. Remove the evaporator.
4. Unsweat the drier from the liquid line.
5. After installing a new water
seal in the new evaporator
(see “To Replace the Water
Seal”) sweat in the new
evaporator at the old tubing
connections.
6. Install an new drier in the
liquid line.
7. Evacuate the system until
dehydrated, then weigh in the
nameplate charge. Check for
leaks.
8. Install auger, breaker,
breaker bearing assembly,
and ice discharge chute in
reverse order of disassembly.
EVAPORATOR
WATER
SEAL
RETAINING RING
To Reassemble the Evaporator and Auger
1. After the gearmotor has been inspected, fasten
the evaporator to the gear motor, be sure that the
number of shims indicated on the gear case cover
is in place between the gearcase cover and the
drip pan gasket. Torque the bolts to 110 inch
pounds.
2. Lower the auger into the evaporator barrel,
slightly turning it to match up with the drive end. Do
Not Drop Into the Evaporator.
3. Complete the reassembly by reversing the
disassembly for the breaker & thrust bearing
assembly.
BREAKER
ICE SWEEP
DRIP PAN
BREAKER
COVER
BEARING
AUGER
May 2001
Page 26
MDT6N90
TO REMOVE AND REPAIR THE GEARMOTOR ASSEMBLY
(Assuming that the procedures through removal of
the water seal have been performed.)
1. Remove the electrical wires from the gear drive
motor.
Electrical Shock Hazard.
Disconnect electrical
power to the icemaker dispenser before
beginning.
2. Unscrew the 4 cap screws holding the
gearmotor to the gearmotor plate.
3. Remove the gearmotor from the
icemaker.
To Inspect the gearmotor.
A) Remove the cap screws holding
the gearmotor case halves together
and pry the two cases apart.
B) To lift off the cover, lift up until
you can feel internal contact, then
pull the cover towards the output
gear end, and then lift the cover
GEARCASE
COVER
(with drive motor attached) up and
away from the gear motor case.
Note: The case cover output gear,
bearings, and shaft are one pressed
together assembly. Replace as a
unit.
C) Inspect the oil, gears, and
bearings. If the oil level and
condition is acceptable, quickly
check the gears and bearings. They
are likely to be fine if the oil is.
If there is evidence of water in the
oil (rusty bearings and gears; the oil
having a creamy white appearance;
oil level too high) carefully inspect
the bearings and gears. If in doubt
about the condition of a part,
replace it. The oil quantity is 14 fluid
ounces, do not overfill.
Note: The gears and bearings are
available only as pressed together
sets.
D) After replacing parts as required, (if any)
reassemble the gearcase. The two smaller gears
and the oil should be in the lower case, the output
gear will be with the cover. As you lower the cover
onto the lower case, cover will have to be moved
closer to the second gear after the output gear has
cleared the second gear top bearing.
E) After the case is together, and the locating pins
are secure in both ends, replace all cap screws.
4. Bench test the gearmotor, check for oil leaks,
noise, and amp draw.
WATER
SHED
MOTOR
GEAR &
BEARINGS
GEAR &
BEARINGS
GASKET
GEAR CASE
SWITCH
BEARING
May 2001
Page 27
MDT6N90
SCALE
REFRIGERATION SERVICE
General: This ice machine uses R-404A refrigerant
and polyolester oil. Do NOT use mineral oil in this
refrigeration system.
When the system is serviced, a special liquid
·
line drier is required. It is included with
replacement compressors.
R-404A is not compatible with mineral oil so
·
these ice machines use Polyolester oil.
Polyolester oil absorbs water very easily. A
system opened for service must be re-sealed as
soon as possible (15 minutes maximum).
Special leak detection equipment is required to
·
locate small refrigerant leaks. Usually a leak
detector capable of detecting a Halongenated
refrigerant or HFC-134a will work. Check with
the leak detector manufacturer if in doubt.
Evacuate to 300 microns.
·
Liquid charge the system
·
Access Valves: To use the
access valves:
Remove the cap from the
·
stem, use a 3/16" allen
wrench to check that the
valve is CLOSED. The
remove the core cap.
·
Close the valve and
replace the caps when done. The valve must be
closed and the caps must be on or the valve will
leak.
Sight Glass
Torque stem
to 6-8 ft.-lb.,
caps to 7-12
ft.-lb.
R-404A
Tank Must
Be in Liquid
Dispensing
Position Check Tank!
Instructions for Liquid Charging R-404A
In preparation for charging, the low side hose
should have a sight glass, and/or a restricting
device (such as a “Charge Faster”) installed in it for
metering liquid into the low side of the system.
1. After a thorough evacuation shut off the manifold
valves and switch off the vacuum pump.
2. Place a drum of R-404A onto an electronic
scale.
3. Attach the charging hose to the drum.
4. Open the valve on the drum and purge the
charging hose.
5. Zero out the scale.
6. Shut the low side access valve at the ice
machine.
7. Open the discharge manifold valve full open.
8. Watch the scale, when the correct charge is
shown, shut the manifold valve.
Note: If all of the charge will not “go in” the
discharge side:
A. Shut the discharge access valve at the ice
machine.
B. Switch the machine on.
C. Open the low side access valve at the ice
machine.
D. Open the low side manifold valve and observe
the sight glass to be certain that only gas is flowing
into the system.
E. When the proper charge is indicated on the
scale, shut off the manifold valve(s).
9. Shut off the valve on the refrigerant drum.
10. Re-open the manifold valves until all liquid has
flowed out of the hoses.
11. Shut the low side access valve on the ice
machine.
12. Remove hoses from ice machine and replace
all caps.
Hose Connection Schematic for Liquid Charging
May 2001
Page 28
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