Scotsman NM1250R User manual

INTRODUCTION
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 system.
The NM1250R is a remote condenser modular
ice system that produces up to 1400 lbs. of
nugget ice in 24 hours at 900F. air and 700F.
water.
It features: front service for the freezer,
gearmotor, control box, water reservoir, and
bin control; stackable with kit KSTACK30; an
electronic circuit for monitoring ice and water
level; a thermostatic expansion valve; and
R-502 as the refrigerant.
TABLE OF CONTENTS
For the Installer
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Remote Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
For the Plumber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
For the Electrician . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Final Check List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Component Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Maintenance & Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Service Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Removal and Replacement
Water Reservoir & Bin Controls . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Bearing & Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Auger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Watert Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Evaporator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Gearmotor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Circuit Board Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Parts Lists and Wiring Diagrams are located in the center of this manual, printed on yellow
paper.
NM1250R
November, 1988
Page 1

The NM1250R is designed to fit the following
Scotsman storage bins:
B590 and extensions (with bin top KBT18)
HTB500 or BH500
BH800 using bin top KBT15
BH1000 using bin top KBT16
When installing a new system, check to be
sure that you have everything you need
before beginning:
Correct Condenser
Correct Bin
Correct Ice Machine
Correct Bin Top (if required)
Correct Precharged line set
Fan Relay kit (if needed)
All kits, legs, and information required for the
specific job.
FOR THE INSTALLER
SPECIFICATIONS: ICEMAKER
+ Minimum Circuit Ampacity is used to determine wire size per National Electric Code.
The standard finish is enamel sandalwood. A stainless steel panel kit, SPKCMD-1, may be field
installed to convert the unit to a stainless steel finish.
MODEL DIMENSIONS
(without bin)
H" x W" x D"
NM1250RE-32A
NM1250RE-3A 27 x 30 x 24 same
COND.
TYPE
REM0TE-
AIR
COMP.
H.P.
1.75
same
BASIC
ELECTRICAL
208-230/60/1
208-230/60/3
MINIMUM
CIRCUIT
AMPACITY+
9.5
na
MAXIMUM
FUSE
SIZE
20
na
ICE
TYPE
NUGGET
same
NM1250R
November, 1988
Page 2

Installation Limitations:
This ice system is designed to be installed indoors,
in a controlled environment: Min Max
Air Temperature 500F 1000F
Water Temperature 400F 1000F
Water Pressure 20 psi 80 psi
Voltage 5% +10%
(Compared to the nameplate)
The temperature limitations do not apply to the
remote condenser. It will work between -20
degrees F, and 120 degrees F.
Operating the machine outside of the limitations is
misuse and can void the warranty.
Scotsman Ice Systems are designed and
manufactured with the highest regard for safety
and performance. They meet or exceed the
standards of UL, NSF, and CSA.
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 part 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 design are subject to change
without notice.
FOR THE INSTALLER
Drain
3/4"
FPT
21"
1.19"
Typical Storage Bin: BH800
Back View
Side View
24"
14.69"
22.38"
31.5"
4.56"
42"
44"
32"
6"
5"
Front View
NM1250R
November, 1988
Page 3

1/2" MALE QUICK CONNECT
COUPLING FOR USE WITH RT625
OR RT640 PRECHAGED LINE SET
LIQUID LINE 3/8" MALE QUICK CONNECT
COUPLING FOR USE WITH RT625 OR
RT640 PRECHARGED LINE SET
32.56"
5.38"
7.5"
3.5" 6.5"
27.81"
7.94"
19.88"
22"
5.75"
5"
FOR THE INSTALLER: Remote Condenser
SPECIFICATIONS: REMOTE CONDENSER
+ Included with minimum circuit ampacity for the icemaker. Use this valve to determine wire size
and type between ice maker and fan motor.
RT625 Precharged line set, 25’. R502.
RT640 Precharged line set, 40’. R502.
KCMR230 Fan relay kit used when two icemakers are on one two circuit condenser.
MODEL DIMENSIONS
H" x W" x D" USE WITH BASIC ELECTRICAL MINIMUM CIRC. AMPACITY+ SHIPPING WEIGHT
RC1051-32A
RC1052-32A 27.81" x 22" x 37.94" same 1 NM1250R 1 or 2 NM1250Rs 208-230/60/1 same 2 same 84 lbs. same
ICEMAKER NAMEPLATE
LOCATED ON BACK PANEL
SERIAL PLATE LOCATED
BEHIND FRONT PANEL
NM1250R
November, 1988
Page 4

Location:
After uncrating and inspection, the unit
is ready for installation. It is important
that the machine be installed in a
location where it has enough space
around it to be accessible for service,
usually a minimum of 6 inches. Try to
avoid hot, dirty and crowded locations.
Be sure that the location for the
machine is within the limitations
described on page 3.
Storage Bin:
Tip the storage bin on its back, using
parts of the carton to protect the exterior
finish. Install the legs into the threaded
holes in the bottom of the bin. Turn the
leg levelers all the way in preparation
for leveling later. Return the bin to the
upright position, remove paper covering
the bin gasket.
Install bin top if required, follow the
directions included with the bin top.
Note: Do not push bin into position, but
lift it there. Pushing a bin, especially
one with ice in it, can cause damage to
the legs and the leg mounts.
Ice Maker:
The machine is heavy, so the use of a
mechanical lift is recommended for
lifting the machine high enough to install
on top of the bin. After the unit is placed
on the bin, line it up so it is even with
the back, left, and right sides. Secure
the machine to the bin with the
hardware provided with the machine.
Remove the front panel and remove the
styrofoam shipping blocks from under
the gearmotor, the top of the ice chute, and
from between the gearmotor and the right side
panel.
FOR THE INSTALLER
LEVEL THE ASSEMBLY
FASTEN THEMACHINE
TO THE BIN WITH THE
HARDWARE SUPPLIED
WITH THE ICEMAKER
GASKET
NM1250R
November, 1988
Page 5

FOR THE INSTALLER: Remote Condenser Installation
Location:
Limited to a 40 foot or a 25 foot length of
precharged refrigerant tubing connecting the
icemaker to the remote condenser. The
condenser must be above or level with the
highest (if stacked) icemaker.
Select the best available location, protecting
the condenser from extremes of dirt, dust, and
sun.
Meet all applicable building codes. Usually
the services of a licensed electrician are
required.
Roof Attachment:
1. Install and attach the remote condenser to
the roof of the building, using the methods and
practices of construction that conform to the
local building codes, including having a
roofing contractor secure the condenser to the
roof.
2. Have an electrician connect the remote
condenser fan motor to the icemaker, using
the junction box at the back of the icemaker.
PRECHARGED LINE ROUTING
/////////////////////////////CAUTION/////////////////////////////
Do not connect precharged tubing until all
routing and forming of the tubing is complete.
See the coupling instructions, next page for
connecting instructions.
//////////////////////////////////////////////////////////////////////////
1. Each set of precharged refrigerant lines
(either 25 foot or 40 foot) consists of a 3/8 inch
diameter liquid line and a 1/2 inch diameter
discharge line. Both ends of each line have
quick connect couplings, one end has a
schrader valve connection, that end goes to
the condenser.
Note: The openings in the building ceiling or
wall, listed in the next step, are the minimum
sizes recommended for passing the refrigerant
lines through.
2. Have the roofing contractor cut a minimum
hole for the refrigerant lines of 1 3/4 inch.
Check local codes, a separate hole may be
required for the electrical power to the
condenser.
//////////////////////////////CAUTION/////////////////////////////
DO NOT KINK OR CRIMP REFRIGERANT
TUBING WHEN INSTALLING IT.
//////////////////////////////////////////////////////////////////////////
3. Route the refrigerant lines through the roof
opening.
Follow straight line routing whenever possible.
Any excess tubing MUST be retained within
the building.
4. Spiral the excess length of pre charged
tubing inside the building. Use a horizontal
spiral (as illustrated) to avoid any traps in the
lines.
5. Have the roofing contractor seal the holes
in the roof per local codes.
REMOTE CONDENSER
LOCATE REMOTE
CONDENSER
ABOVE ICEMAKER
SPIRAL
EXCESS
TUBING
INSIDE
BUILDING
NM1250R
November, 1988
Page 6

COUPLING INSTRUCTIONS
///////////////////////////CAUTION//////////////////////////////
The couplings on the sets of precharged lines
are self sealing when installed properly.
Carefully follow the instructions:
//////////////////////////////////////////////////////////////////////////
1. Remove the protector caps and plugs.
Wipe the seats and threaded surfaces with a
clean cloth to be certain that no foreign matter
remains on them.
2. Lubricate the inside of the couplings,
especially the O-Rings with refrigerant oil.
3. Begin tightening the couplings together by
hand, then using two wrenches (it is important
that ONLY the nut on the precharged lines be
turned, the other parts of the couplings must
NOT be allowed to turn or the process will tear
out the diaphragms and they will be loose in
the refrigeration system) tighten the coupling
until it bottoms out or a definite increase in
resistance is felt.
4. Using a marker or pen, mark a line
lengthwise from the coupling union nut to the
bulkhead. Then tighten the coupling and
additional 1/4 turn. As the nut turns, the line
will show when 1/4 turn is made.
5. Connect the 3/8 inch liquid line (schrader
valve end) to the remote condenser fitting
marked "liquid line".
6. Connect the other end of the liquid line to
the icemaker fitting marked "liquid line."
7. Connect the 1/2 inch discharge line
(schrader valve end) to the remote condenser
fitting marked "discharge line".
8. Connect the other end of the liquid line to
the icemaker fitting marked "discharge line".
9. After all connections are made, and after
the king valve has been opened, check the
couplings for leaks.
FOR THE INSTALLER
SCHRADER VALVE NO SHRADER
VALVE
TO REMOTE
CONDENSER TO ICEMAKER
SERVICE PORTS
REMOTE
CONDENSER
3/8" LIQUID LINE
1/2" DISCHARGE LINE
NM1250R
November, 1988
Page 7

////////////////////////////WARNING///////////////////////////
ELECTRICAL POWER MUST BE OFF
WHEN CONNECTING WIRES
/////////////////////////////////////////////////////////////////////////
1. Install the lower unit onto the bin.
2. Remove the top panel from the lower unit.
3. With the aid of a mechanical hoist, lift the
upper machine onto the top of the lower unit.
Align the rear, left, and right side panels.
4. Secure the bottom machine to the top
machine with the hardware provided with the
top unit: 4 cap screws, and 2 metal straps.
5. Use stacking kit KSTACK30:
a) In the lower unit, remove the ice chute
cover.
b) In the upper unit, temporarily remove the
ice discharge chute.
c) In the lower unit, insert the chute from the
kit into the hole in the base of the upper unit,
temporarily push it up into the base.
d) In the lower unit, install the new ice chute
cover, then slide the connecting chute down
into the hole in the new cover.
e) In the upper unit, reinstall the ice chute and
cover. Remove the upper unit bin control
sensors from their circuit board connections.
Install the relay from the kit in the location
illustrated.
f) Install interconnecting wires from the kit
between the upper unit circuit board "opto"
(purple wire) and "LED" (yellow wire)
connections and the relay:
Purple to terminal 9.
Yellow to terminal 6.
Install wire harness from lower unit through
the hole in the base, and connect to the relay
terminals A & B.
g) In the lower unit, remove the wire harness
from the transformer to the circuit board.
Connect new wire harness (just routed from
the upper unit) onto transformer and circuit
board.
Replace the front panels.
Note: When started, the lower unit will start
first, then the upper.
FOR THE INSTALLER: Stacking
NM1250R
November, 1988
Page 8

FOR THE PLUMBER
CONFORM TO ALL APPLICABLE CODES
Water Inlet
The recommended water supply is cold water.
Use 3/8" O.D. copper tubing, connect to the
3/8" male flare at the back of the cabinet.
Install a hand valve near the machine to
control the water supply.
Drains
There is one 3/4" FPT drain at the back of the
cabinet, the drain line is of the gravity type,
and 1/4 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 3/4" rigid tubing.
Storage Bin: A separate gravity type drain
needs to be run. Insulation of this drain line is
recommended.
WATER
INLET
3/8" FLARE
HAND
SHUT OFF
VALVE
CONNECT TO
COLD WATER
FIELD INSTALLED
FILTER
(OPTIONAL)
ICEMAKER DRAIN
3/4" FPT
BIN DRAIN
3/4" FPT
NM1250R
November, 1988
Page 9

FOR THE ELECTRICIAN
CONFORM TO ALL APPLICABLE CODES
The electrical power to the unit is
supplied through 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.
Electrically the remote condenser fan
motor is connected to the icemaker at
the contactor terminals for the
compressor and the fan motor
operates whenever the compressor
operates.
Electrical connections are made at the
junction box at the back of the
icemaker and at the junction box on
the remote condenser.
The remote condenser must be wired
to the icemaker in accordance with
local and national electrical codes with
a minimum of 18 Awg. wire with an
ground bonding wire connected to the
ground screws provided in both the
condenser and machine field wiring
boxes. All outdoor wiring must be in
rainproof conduit.
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.
REMOTE CONDENSER
WATERPROOF
(LIQUID TIGHT)
CONDUIT
ICEMAKER
JUNCTION BOX
POWER
SUPPLY
NM1250R
November, 1988
Page 10

FOR THE ELECTRICIAN FAN RELAY KIT
To install the KCMR230 fan relay kit when
using (2) NM1250R icemakers and one 230
volt, two circuit remote condenser.
//////////////////////////////WARNING//////////////////////////
Do all wiring with electrical power OFF.
//////////////////////////////////////////////////////////////////////////
See the remote condenser nameplate for
current requirements to determine wire size to
be used for electrical hookup. Refer to wiring
diagram.
All external wiring should conform to the
national, state and local electrical codes.
Usually an electrical permit and services of a
licensed electrician will be required.
1. Mount the control box in a convenient
location.
2. Attach a solid earth ground wire to the
ground screw.
3. Route connecting wires from the first ice
maker junction box
(marked condenser fan) and connect it to the
KCMR230 terminal strip marked: NO. 1 ICE
MACHINE.
4. Route connecting wires from the second
machine junction box
(marked condenser fan) and connect it to the
KCMR230 terminal strip marked: NO. 2 ICE
MACHINE.
5. Route connecting wires from KCMR230
terminal strip marked: TO REMOTE FAN and
connect at the remote condenser junction box.
SUGGESTED
LOCATION
FOR KCMR230
CONTROL BOX
NM1250R
November, 1988
Page 11

6. Check phasing of the electrical circuit as
follows:
A. The phasing of the wiring MUST now be
checked, as incorrect phasing will result in a
failure of the kit relay.
Below is an illustration of the KCMR230
terminal strip. Note that each terminal is
marked: 1-2-3-4-5-6. For proper phasing:
Terminals #1 and #3 must be connected to
the same side of the line (such as L1)
Terminals #2 and #4 must be connected to
the same side of the line (such as L2).
B. Make a test with a volt meter as follows:
1. Switch on icemaker #1 first, then switch on
icemaker #2.
(The compressors must be operating for this
test. Do this after start up.)
2. Test with a volt meter between terminals
#2 and #4, then between terminals #1 and #3.
Compare the readings obtained to the ones in
the following list:
C. Test terminals 1-2 = Full Voltage (208-230)
Test terminals 1-3 = No voltage
Test terminals 2-3 = Full Voltage
Test terminals 2-4 = No voltage
Test terminals 3-4 = Full voltage
Test terminals 1-4 = Full voltage
D. If there is full voltage where there should
be no voltage, turn off icemaker #2, (both
switches) Then turn off icemaker #1 (both
switches). The connections at the KCMR230
terminal strip marked icemaker #1 must be
reversed (put the wire that was on 1 on 2 and
the wire that was on 2 on 1).
FOR THE ELECTRICIAN (Do this after Start Up)
NM1250R
November, 1988
Page 12

FOR THE INSTALLER: Completed Installation
ROOF
CUT-AWAY
INSULATED PRECHARGED
REFRIGERANT TUBING
A typical installation should generally appear
as illustrated below. The remote condenser
must be located above the icemaker and the
precharged lines installed per the instructions
on page 6.
NM1250R
November, 1988
Page 13

FOR THE INSTALLER: Final Check List
1. Is the ice system installed
indoors in a location where the air
and water temperatures are
controlled, and where they do not
exceed the design limitations?
2. Is there an electrical service
disconnect within sight of the
installed machine? Has the
voltage been checked, and
compared to nameplate
requirements?
3. Have all the plumbing
connections been made and
checked for leaks?
4. Has the machine and bin been
leveled?
5. Is there a minimum of 6"
clearance at the rear, left, and right
of the machine for proper service
access and air circulation?
6. Is the water pressure a
minimum of 20 psig?
7. Has the machine been secured
to the bin?
8. If stacked, has the stacking kit
been installed?
9. Is there a water shut off valve
installed near the machine?
10. Is the remote condenser
installed per local building codes,
and in a place where it has
adequate ventilation and minimal
solar heat gain?
11. Has all shipping material
(under and next to the gearmotor,
and on top of the ice chute) and
literature (inside the front panel)
been removed from the units?
12. Have the remote condenser
and precharged lines been
properly installed?
13. Has the electrical connection
between the icemaker and the condenser
been made?
14. Verify that the master switch is in the OFF
postion.
15. Switch on the electrical power.
16. Refer to Pre-Start instructions, the next
page.
LEVELED?
POWER SUPPLY?
PLUMBING?
DRAINS?
NM1250R
November, 1988
Page 14

START UP
Pre-Start Inspection
1. Remove the front, left, and right side
service panels.
2. Check that the styrofoam shipping blocks
under the gearmotor, on top of the ice
dischage chute, and between the gearmotor
and the right side panel have been removed.
3. 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 turns freely (remote condenser).
4. Check that the refrigerant lines are properly
installed.
5. Check that the electrical power has been
on for at least 12 hours and that the
compressor dome is warm.
6. Check that the unit is installed corerectly
according to the final check list on page 14.
Start Up
1. Go through the pre-start inspection.
2. Open the 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. Open the King Valve.
4. Turn the master switch on, and press the
start/reset switch.
The electrical start up sequence is now on
automatic.
A. There should be a short (15 second) delay
before the gearmotor starts.
B. After the gearmotor starts, the liquid line
valve will open, the pump down control will
close and the compressor will start.
5. The remote condenser fan turns, and the
condenser begins to discharge warm air.
6. The unit should soon be making ice, if
desired the low side pressure can be checked,
it should be 30 psig + or - 4 psig. The
discharge pressure will depend upon air and
water temperatures, but should be between
200 psig and 280 psig.
Gearmotor amps should be about 1.2.
Compressor (single phase) amps should be
about 7.1
7. THERE ARE NO ADJUSTMENTS TO
MAKE, so replace the panels.
8. Clean and/or sanitize the storage bin
interior, wipe off the exterior with a clean,
damp cloth.
9 Give the owner/user the service manual,
instruct him/her in the operation of the unit,
and make sure they know who to call for
service.
10. Fill out the manufacturers registration
card, and mail it to the Scotsman Factory.
11. Fill out the field quality audit form, and mail
it to the Scotsman factory.
NM1250R
November, 1988
Page 15

COMPONENT DESCRIPTION
Control Box: Contains the electrical controls
that operate the machine.
High Pressure Cut Out (control): A manual
reset switch sensing the high side refrigeration
pressure. It is set to shut the machine off at
450 psig.
Reset Switch: Manual reset. Glows when the
unit shuts off from ice discharge chute being
overfilled (opening the microswitch at the top
of the chute), or if either of the pressure cut
out switches opens.
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 Discharge Chute: Directs the ice
produced by the evaporator into the storage
bin.
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.
Gear Motor: An oil filled, speed reduction
gearbox, driving the auger.
Cleaning Drain Tube: When uncapped and
lowered, drains the evaporator.
Compressor: The refrigerant vapor pump.
Expansion valve: The refrigerant metering
device.
RESET SWITCH
ICE CHUTE
EXPANSION VALVE
GEAR MOTOR
EVAPORATOR
CLEANING DRAIN
TUBE
ICE LEVEL SENSORS
RESERVOIR
WATER LEVEL SENSOR
(INSIDE RESERVOIR)
COMPRESSOR
HIGH PRESSURE
CUT OUT
NM1250R
November, 1988
Page 16

COMPONENT DESCRIPTION: Control Box
Contactor: A definite purpose contactor
connecting the compressor and the remote
condenser fan motor to the power supply.
Circuit Board: Controlling the ice machine
through sensors and relays. The sensors are:
ice level, and water level. The relays are for
the gear motor (with a built in time delay to
clear the evaporator of ice when the unit turns
off) and for the liquid line valve.
Transformer: Supplies low voltage to the
circuit board.
Pump Down Control: A switch to control the
compressor, depending upon low side
pressure: closes at 18 PSIG, and opens at 8
PSIG.
Potential Relay: The compressor start relay.
On/Off Switch: Manual control for the
machine.
Reset Switch: Manual reset. Glows when the
unit shuts off from ice discharge chute being
overfilled (opening the microswitch at the top
of the chute), or if either of the pressure cut
out switches opens.
PUMP DOWN
CONTROL
SWITCH
OF/OFF
SWITCH
CONTACTOR
RESET SWITCH
POTENTIAL
RELAY
TRANSFORMER
CIRCUIT
BOARD
NM1250R
November, 1988
Page 17

ELECTRICAL SEQUENCE
Refer the wiring diagram as needed.
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 light on the circuit board
goes on
••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 liquid line relay and auger motor relay
become energized, connecting power to the
liquid line solenoid coil and the windings of
the auger motor.
••The liquid line solenoid opens, raising the
low side pressure.
••The pump down control closes
••The auger motor starts, and the centrifugal
switch closes, connecting power to the
compressor contactor coil.
••The contactor is energized, connecting
power to the compressor, and the
compressor starts.
••As ice goes past the ice level sensors, the
bin empty light will be 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
machine shuts down.
Shut Down consists of:
••The liquid line solenoid relay opens,
lowering the suction pressure.
••The pump down pressure control opens.
••The compressor contactor opens
••The compressor stops
••The auger motor is run by the circuit board
for 2.5 more minutes, clearing out ice in the
evaporator, and then
••The auger motor relay opens, and the
auger motor stops.
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 water level sensor, the machine
will "shut down"
••When the water refills the reservoir, the
machine will start up again.
Separate from the circuit board:
••If the high pressure control (cut out) opens,
the machine will stop immediately (through
the relays on the circuit board) and cause
the reset switch on the circuit board to light
up. It must be manually reset at the control
and at the reset switch on the circuit board.
••The pump down control switch will stop &
start the compressor.
••If the spout switch opens the machine will
stop immediately (through the relays on the
circuit board) and cause the reset switch on
the circuit board to light up. It is a manual
reset at the circuit board.
The master switch is the manual control for
the complete machine, but it is not a service
disconnect.
NM1250R
November, 1988
Page 18

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 or evaporator
condensation is routed to the drain.
RESERVOIR EVAPORATOR
DRAIN
WATER LEVEL
STRAINER
WATER
INLET
DRAIN
ADJUSTMENT OF THE
WATER LEVEL
NM1250R
November, 1988
Page 19

OPERATION:
Beginning at the compressor, the refrigerant
502 is compressed into a high temperature
gas. The discharge line directs this gas to the
condenser and to the head pressure control
At the remote condenser the gas is cooled
by air and it then condenses into a liquid. This
high pressure liquid then goes through the
liquid line to the liquid line connection at the
head pressure control. If the head pressure
is high enought the liquid refrigerant will go
through the valve and enter the receiver.
From the receiver, the liquid refrigerant flows
through the liquid line valve and then 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. 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.
REMOTE CONDENSER
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
LIQUID LINE
VALVE
THERMOSTATIC
EXPANSION
VALVE
EVAPORATOR
COMPRESSOR
HIGH PRESSURE
CONTROL SWITCH
RECEIVER
HEAD
PRESSURE
CONTROL
VALVE
DISCHARGE
LINE
LIQUID LINE
NM1250R
November, 1988
Page 20