Manitowoc Q 1800 User manual

Marine
Q 1800
Ice Machine
Service Manual
Thank you for selecting a Manitowoc Ice Machine, the dependability leader in ice making equipment and
related products. With proper installation, care and maintenance, your new Manitowoc Ice Machine will
provide you with many years of reliable and economical performance.
Part Number 80-1211-3
7/00

Safety Notices
When using or servicing a Q Model Ice Machine, be
sure to pay close attention to the safety notices in this
manual. Disregarding the notices may lead to serious
injury and/or damage to the ice machine.
Throughout this manual, you will see the following
types of safety notices:
WARNING
Text in a Warning box alerts you to a potential
personal injury situation. Be sure to read the
Warning statement, and then proceed carefully.
CAUTION
Text in a Caution box alerts you to a situation in
which you could damage the ice machine. Be sure
to read the Caution statement, and then proceed
carefully.
Procedural Notices
When using or servicing a Q Model Ice Machine, be
sure to read the procedural notices in this manual.
These notices supply helpful and important
information.
Throughout this manual, you will see the following
types of procedural notices:
Important
Important boxes serve two functions.
They call the operator’s attention to important
information.
They also provide the service technician with
information that may help perform a procedure
more efficiently. Disregarding this information may
slow down the work.
NOTE: Text set off as a Note provides you with
simple, but useful, extra information.
CAUTION
Proper installation, care and maintenance are
essential for maximum ice production and trouble-
free operation of your Manitowoc Ice Machine.
Read and understand this manual. It contains
valuable care and maintenance information. If you
encounter problems not covered by this manual,
feel free to contact Manitowoc Ice, Inc. We will be
happy to provide assistance.
Important
Routine adjustments and maintenance procedures
outlined in this manual are not covered by the
warranty.

Table of Contents
Electrical System
Energized Parts Charts
Self-Contained Water-Cooled Models...........................................................................................................1
Wiring Diagram Sequence of Operation
Self-Contained Models.....................................................................................................................................2
Wiring Diagrams
Wiring Diagram Legend..................................................................................................................................9
Self-Contained - Q1800 - 1 Phase.................................................................................................................10
Component Specifications and Diagnostics
Main Fuse .......................................................................................................................................................11
Bin Switch.......................................................................................................................................................11
Compressor Electrical Diagnostics...............................................................................................................13
PTCR Diagnostics..........................................................................................................................................14
Ice/Off/Clean Toggle Switch .........................................................................................................................17
Control Board Relays....................................................................................................................................17
Electronic Control Board..............................................................................................................................18
Ice Thickness Probe (Harvest Initiation)
How the Probe Works ...................................................................................................................................20
Harvest/Safety Limit Light ...........................................................................................................................20
Freeze Time Lock-In Feature.......................................................................................................................20
Maximum Freeze Time..................................................................................................................................20
Diagnosing Ice Thickness Control Circuitry
Ice Machine Does Not Cycle Into Harvest When Water Contacts The Ice Thickness Probe..........21
Ice Machine Cycles Into Harvest Before Water Contact With The Ice Thickness Probe................22
Water Level Control Circuitry
Diagnosing Freeze Cycle Potable Water Level Control Circuitry ...........................................................23
Water Trough Overfilling During The Freeze Cycle ...........................................................................24
Water Will Not Run Into The Sump Trough During The Freeze Cycle............................................26
Diagnosing Ice Machine That Will Not Run..........................................................................................27

Table of Contents
Refrigeration System
Sequence of Operation
Self-Contained Water-Cooled Models.........................................................................................................28
Operational Analysis (Diagnostics)
General............................................................................................................................................................29
Before Beginning Service ..............................................................................................................................30
Ice Production Check ....................................................................................................................................30
Installation/Visual Inspection Checklist......................................................................................................31
Water System Checklist ................................................................................................................................31
Ice Formation Pattern ...................................................................................................................................32
Safety Limits...................................................................................................................................................34
Hot Gas Valve Temperature Check.............................................................................................................37
Analyzing Discharge Pressure During Freeze or Harvest Cycle
Procedure..................................................................................................................................................38
Freeze Cycle Discharge Pressure High Checklist.................................................................................38
Freeze Cycle Discharge Pressure Low Checklist..................................................................................38
Analyzing Suction Pressure During Freeze Cycle
Procedure..................................................................................................................................................39
Freeze Cycle Suction Pressure High Checklist .....................................................................................40
Freeze Cycle Suction Pressure Low Checklist......................................................................................40
How to Use the Refrigeration System Operational Analysis Tables.........................................................41
Refrigeration System Operational Analysis Table
Dual TXV..................................................................................................................................................42
Pressure Control Specifications and Diagnostics
High Pressure Cutout (HPCO) Control.......................................................................................................43
Cycle Time/24 Hour Ice Production/Refrigerant Pressure Charts
Q1800 ..............................................................................................................................................................44
Refrigerant Recovery/Evacuating and Recharging
Normal Self-Contained Model Procedures..................................................................................................45
System Contamination Cleanup...................................................................................................................47
Replacing Pressure Controls Without Removing Refrigerant Charge ....................................................49
Filter-Driers....................................................................................................................................................51
Total System Refrigerant Charges...............................................................................................................51
Refrigerant Definitions..................................................................................................................................52
Refrigerant Re-Use Policy.............................................................................................................................53
HFC Refrigerant Questions and Answers...................................................................................................54

1
Electrical System
Electrical System
Energized Parts Charts
SELF-CONTAINED WATER-COOLED MODELS
Ice Making Control Board Relays
Sequence 1 2 3 4 5 5A Length
Of
Operation
Water
Pump
Water Fill
Valve
Hot Gas
Valve(s)
Water
Dump
Valve
Contactor
Coil
Compressor
Of
Time
Start-Up1
1. Water Purge
On Off On On Off Off 45 Seconds
2. Refrigeration System
Start-Up
Off On On Off On On 5 Seconds
Freeze Sequence
3. Pre-Chill
Off Off Off On On 30 Seconds
Freeze
On
May cycle
On/Off
during first
45 sec.
-------------
Cycles On,
then Off 1
more time
Off Off On On
Until 7 sec.
water contact
with ice
thickness
probe
Harvest Sequence
5. Water Purge
On
30 sec.
Off, 15
sec. On
On On On On
Factory-set at
45 Seconds
6. Harvest
Off Off On Off On On Bin switch
activation
7. Automatic
Shut-Off
Off Off Off Off Off Off
Until bin switch
re-closes
1Initial Start-Up or Start-Up After Automatic Shut-Off
Harvest Water Purge
The circuit board has an adjustable water purge in
the harvest cycle. This permits a 15, 30 or 45
second purge cycle.
Auto Shut-Off
The ice machine remains off for 3 minutes before it
can automatically restart. The ice machine restarts
(steps 1-2) immediately after the delay period, if the
bin switch re-closes prior to 3 minutes.
Safety Timers
The control board has the following non-adjustable
safety timers:
FREEZE SEQUENCE
•The ice machine is locked into the freeze cycle
for the first 6 minutes, not allowing the ice
thickness probe to initiate a harvest sequence.
•The maximum freeze time is 60 minutes, at
which time the control board automatically
initiates a harvest sequence (steps 5-6).
HARVEST SEQUENCE
The maximum harvest time is 3-1/2 minutes, at
which time the control board automatically
terminates the harvest sequence. If the bin switch is
open, the ice machine will go to automatic shut-off
(step7). If the bin switch is closed, the ice machine
will go to the freeze sequence (steps 3-4).

2
Electrical System
Wiring Diagram Sequence of
Operation
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(51)
(48)
CONTACTOR
CONTACTS
L1
(42)
(66)
(64)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
SV1646-1
RUN CAPACITOR
RUN CAPACITOR**
C
S
R
TB34
(53)
(47)
(85) (86)
COMPRESSOR
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69) ICE
OFF
CLEAN
(67) (68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
TB30
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
FUSE (7A)
TRANS.
2
4
1
3
5
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
HOT GAS
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
(21) (22)
WATER
VALVE
TB30
TB30
SELF-CONTAINED MODELS
Initial Start-Up or Start-Up After
Automatic Shut-Off
1. WATER PURGE
Before the compressor starts, the water
pump and water dump solenoid are
energized for 45 seconds to purge old water
from the ice machine. This ensures that the
ice-making cycle starts with fresh water.
The hot gas valve(s) is also energized
during the water purge. In the case of an
initial refrigeration start-up, it stays on for
an additional 5 seconds (50 seconds total).
Self-Contained Models 1. Water Purge (45 Seconds)
Toggle Switch ICE
Bin Switch Closed
Control Board Relays
#1 Water Pump Closed / ON
#2 Water Fill Valve Open / OFF
#3 Hot Gas Solenoid Closed / ON
#4 Water Dump Valve Closed / ON
#5 Contactor Coil Open / OFF
Compressor OFF
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

3
Electrical System
Initial Start-Up Or Start-Up After
Automatic Shut-Off (cont.)
2. REFRIGERATION SYSTEM
START-UP
The compressor starts after the 45-
second water purge, and it remains on
throughout the Freeze and Harvest
cycles.
The water fill valve is energized at the
same time as the compressor. It
remains on until the water level sensor
closes for 3 continuous seconds.
The hot gas valve(s) remains on for
the first 5 seconds of the initial
compressor start-up.
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(51)
(48)
CONTACTOR
CONTACTS
L1
(42)
(66)
(64)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
SV1646-2
RUN CAPACITOR
RUN CAPACITOR**
C
S
R
TB34
(53)
(47)
(85) (86)
COMPRESSOR
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69) ICE
OFF
CLEAN
(67) (68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
TB30
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
FUSE (7A)
TRANS.
2
4
1
3
5
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
HOT GAS
(21) (22)
WATER
VALVE
TB30
TB30
Self-Contained Models 2. Refrigeration System Start-Up (5 Seconds)
Toggle Switch ICE
Bin Switch Closed
Control Board Relays
#1 Water Pump Open / OFF
#2 Water Fill Valve Closed / ON
#3 Hot Gas Solenoid Closed / ON
#4 Water Dump Valve Open / OFF
#5 Contactor Coil Closed / ON
Compressor ON
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

4
Electrical System
Freeze Sequence
3. PRE-CHILL
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(51)
(48)
CONTACTOR
CONTACTS
L1
(42)
(66)
(64)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
RUN CAPACITOR
RUN CAPACITOR**
C
S
TB34
(53)
(47)
(85) (86)
COMPRESSOR
R
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69) ICE
OFF
CLEAN
(67) (68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
TB30
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
FUSE (7A)
TRANS.
5
2
4
1
3
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
HOT GAS
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
(21) (22)
WATER
VALVE
TB30
TB30
To pre-chill the evaporator, the compressor runs
for 30 seconds prior to water flow.
The water fill valve remains on until the water
level sensor closes for three continuous
seconds.
Self-Contained Models 3. Pre-Chill (30 Seconds)
Toggle Switch ICE
Bin Switch Closed
Control Board Relays
#1 Water Pump Open / OFF
#2 Water Fill Valve Closed / ON
#3 Hot Gas Solenoid Open / OFF
#4 Water Dump Valve Open / OFF
#5 Contactor Coil Closed / ON
Compressor ON
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

5
Electrical System
Freeze Sequence (cont.)
4. FREEZE
The water pump starts after the 30-
second pre-chill. An even flow of
water is directed across the evaporator
and into each cube cell, where it
freezes.
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(51)
(48)
CONTACTOR
CONTACTS
L1
(42)
(66)
(64)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
SV1646-4
RUN CAPACITOR
RUN CAPACITOR**
C
S
R
TB34
(53)
(47)
(85) (86)
COMPRESSOR
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69) ICE
OFF
CLEAN
(67) (68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
TB30
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
FUSE (7A)
TRANS.
2
4
1
3
5
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
HOT GAS
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
(21) (22)
WATER
VALVE
TB30
TB30
When sufficient ice has formed, the
water flow (not the ice) contacts the
ice thickness probes. After
approximately 7 seconds of continual
contact, a harvest cycle is initiated.
NOTE: The ice machine cannot
initiate a harvest cycle until a 6-
minute freeze lock has expired.
Self-Contained Models
4. Freeze (Until 7 Seconds of Water Contact with Ice Thickness Probe)
Toggle Switch ICE
Bin Switch Closed
Control Board Relays
#1 Water Pump Closed / ON
#2 Water Fill Valve Cycles ON then OFF
#3 Hot Gas Solenoid Open / OFF
#4 Water Dump Valve Open / OFF
#5 Contactor Coil Closed / ON
Compressor ON
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

6
Electrical System
Harvest Sequence
5. WATER PURGE
The water pump continues to run, and
the water dump valve energizes for 45
seconds to purge the water in the sump
trough. The water fill valve energizes
(turns on) and de-energizes (turns off)
strictly by time. The water fill valve
energizes for the last 15 seconds of the
45-second water purge. The water
purge
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(51)
(48)
CONTACTOR
CONTACTS
L1
(42)
(66)
(64)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
SV1646-5
RUN CAPACITOR
RUN CAPACITOR**
C
S
R
TB34
(53)
(47)
(85) (86)
COMPRESSOR
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69) ICE
OFF
CLEAN
(67) (68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
TB30
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
FUSE (7A)
TRANS.
2
4
1
3
5
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
HOT GAS
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
(21)
WATER
VALVE
(22)
TB30
TB30
must be at the factory setting of
45 seconds for the fill valve to
energize during the last 15 seconds of
the Water Purge. If set at less than 45
seconds, the water fill valve does not
energize during the water purge.
After the 45 second water purge, the
water fill valve, water pump and dump
valve de-energize. (Refer to "Water
Purge Adjustment for details.) The hot
gas valve also opens at the beginning
of the water purge to divert hot
refrigerant gas into the evaporator.
Self-Contained Models 5. Water Purge (45 Seconds)
Toggle Switch ICE
Bin Switch Closed
Control Board Relays
#1 Water Pump Closed / ON
#2 Water Fill Valve Cycles OFF then ON
#3 Hot Gas Solenoid Closed / ON
#4 Water Dump Valve Closed / ON
#5 Contactor Coil Closed / ON
Compressor ON
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

7
Electrical System
Harvest Sequence (cont.)
6. HARVEST
The hot gas valve(s) remains open,
allowing refrigerant gas to warm the
evaporator. This causes the cubes to
slide, as a sheet, off the evaporator and
into the storage bin.
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(51)
(48)
CONTACTOR
CONTACTS
L1
(42)
(66)
(64)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
SV1646-6
RUN CAPACITOR
RUN CAPACITOR**
C
S
R
TB34
(53)
(47)
(85) (86)
COMPRESSOR
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69) ICE
OFF
CLEAN
(67) (68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
TB30
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
FUSE (7A)
TRANS.
2
4
1
3
5
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
HOT GAS
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
(21) (22)
WATER
VALVE
TB30
TB30
The sliding sheet of cubes swings the
water curtain out, opening the bin
switch. This momentary opening and
closing of the bin switch terminates
the Harvest Cycle and returns the ice
machine to the Freeze Cycle (steps 3-
4).
Self-Contained Models 6. Harvest (Until Bin Switch Activation)
Toggle Switch ICE
Bin Switch Closed
Control Board Relays
#1 Water Pump Open / OFF
#2 Water Fill Valve Open / OFF
#3 Hot Gas Solenoid Closed / ON
#4 Water Dump Valve Open / OFF
#5 Contactor Coil Closed / ON
Compressor ON
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

8
Electrical System
7. Automatic Shut-Off
If the storage bin is full at the end of a
harvest cycle, the sheet of cubes fails
to clear the water curtain and holds it
open. After the water curtain is held
open for 7 seconds, the ice machine
shuts off.
*OVERLOAD
FAN CYCLE CONTROL
BIN SWITCH
TB35
TB33 (52)
(48)
CONTACTOR
CONTACTS
L1
(42)
(51)
(64)
(66)
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
TB35
HIGH PRES
CUTOUT
TB32
L1
(55)
SV1646-7
TB30
RUN CAPACITOR
RUN CAPACITOR**
S
R
TB34
(47)
(86)
COMPRESSOR
C
(53)
(85)
FAN MOTOR
(AIR COOLED ONLY)
RR
(45)
(46) (50)
PTCR
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
CLEAN LIGHT
WATER LEVEL
(49)
(63)
(62)
(66)
(65)
(69)
(67) ICE
OFF
CLEAN
(68)
1F
1C
LOW D.C.
VOLTAGE
PLUG
(62)
1G
TOGGLE SWITCH
68
67
69
66
62
VIEW FOR WIRING
INTERNAL WORKING
VIEW
TB37
(74)
(59)
(73)
(56) CONTACTOR
COIL
TERMINATES AT
PIN CONNECTION
T
B30
TB30
TB30
L2 (N)
SEE SERIAL PLATE FOR VOLTAGE
(58)
4
1
3
5
FUSE (7A)
TRANS.
2
(61)
(60)
TB31
(76)
(98)
(57)
(99)
(75)
HOT GAS
SOLENOID
DUMP
SOLENOID (81)
WATER
PUMP
(77)
(80)
(21) (22)
WATER
VALVE
TB30
TB30
The ice machine remains off until
enough ice is removed from the
storage bin to allow the sheet of cubes
to drop clear of the water curtain. As
the water curtain swings back to the
operating position, the bin switch
closes and the ice machine restarts
(steps 1-2).
NOTE: The ice machine must remain
off for 3 minutes before it can
automatically restart.
Self-Contained Models 7. Automatic Shut-Off (Until Bin Switch Closes)
Toggle Switch ICE
Bin Switch Open
Control Board Relays
#1 Water Pump Open / OFF
#2 Water Fill Valve Open / OFF
#3 Hot Gas Solenoid Open / OFF
#4 Water Dump Valve Open / OFF
#5 Contactor Coil Open / OFF
Compressor OFF
Safety Controls (Which could stop ice machine operation)
High Pressure Cut-Out Closed
Main Fuse (On Control Board) Closed

9
Electrical System
Wiring Diagrams
The following pages contain electrical wiring diagrams. Be sure you are referring to the correct diagram for
the ice machine which you are servicing.
WARNING
Always disconnect power before working on
electrical circuitry.
WIRING DIAGRAM LEGEND
The following symbols are used on all of the wiring diagrams:
*Internal Compressor Overload
(Some models have external compressor overloads)
TB Terminal Board Connection
(Terminal board numbers are printed on the actual terminal board)
( ) Wire Number Designation
(The number is marked at each end of the wire)
⎯>>⎯ Multi-Pin Connection
(Electrical Box Side) ⎯>>⎯ (Compressor Compartment Side)

10
Electrical System
Q1800 - 1 PHASE
(61)
(
74
)
L1
TB30
TB30
TB30
TB30
SEE SERIAL PLATE FOR VOLTAGE
L2 (N)
CAUTION: DISCONNECT POWER BEFORE
WORKING ON ELECTRICAL CIRCUITRY.
NOTE: DIAGRAM SHOWN DURING FREEZE CYCLE.
TB32
(
55
)
(
61
)
(
60
)
(
77
)
(
76
)
(
80
)
(
75
)
(
98
)
(
57
)
(
99
)
(
81
)
(
58
)
(
59
)
(
73
)
(
56
)
TB31
TB37
3
1
2
4
TRANS.
FUSE
(
7A
)
HIGH
PRESSURE
CUT-OUT LH HOT GAS
SOLENOID
DUMP
SOLENOID
WATER
PUMP
TERMINATES AT
PIN CONNECTION
CONTACTOR
COIL
5
(
21
)
(
22
)
WATER
V
ALVE
35 TB
(
88
)
(
87
)
RH HOT GAS
SOLENOID
L1
(
49
)
(
48
)
35 TB30
TB30
1C
1F
ICE THICKNESS PROBE
LOW D.C.
VOLTAGE
PLUG
WATER LEVEL PROBE
BIN SWITCH
(
62
)
(
63
)
(
64
)
(
65
)
(
66
)
(
66
)
(
67
)
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
BIN SWITCH LIGHT
(
68
)
VIEW FOR WIRING
66 67
68
69
62
TOGGLE SWITCH
CLEAN
OFF
ICE ←INTERNAL
WORKING VIEW
WATER LEVEL LIGHT
CLEAN LIGHT
1G
AUCS DISPENSE TIME
(
69
)
(
62
)
TB
(
47
)
*OVERLOAD
CONTACTOR
CONTACTS
(
42
)
SR
C
(
50
)
PTCR
)
COMPRESSOR
TB35
(
95
)
(
94
)
CRANKCASE HEATER
(
46
)
(
45
)
(
44
)
RUN CAPACITOR
RR
CONTACTOR
CONTACTS
(
96
)
L2
SV1652

11
Electrical System
Component Specifications and Diagnostics
MAIN FUSE BIN SWITCH
Function Function
The control board fuse stops ice machine operation
if electrical components fail causing high amp
draw.
Bin switch operation is controlled by movement of
the water curtain. The bin switch has two main
functions:
1. Terminating the harvest cycle and returning the
ice machine to the freeze cycle.
Specifications
The main fuse is 250 Volt, 7 amp. This occurs when the bin switch is opened and
closed again within 7 seconds during the harvest
cycle.
Check Procedure
WARNING
High (line) voltage is applied to the control board
(terminals #55 and #56) at all times. Removing
the control board fuse or moving the toggle
switch to OFF will not remove the power
supplied to the control board.
2. Automatic ice machine shut-off.
If the storage bin is full at the end of a harvest
cycle, the sheet of cubes fails to clear the water
curtain and holds it open. After the water curtain
is held open for 7 seconds, the ice machine
shuts off.
1. If the bin switch light is on with the water
curtain closed, the fuse is good.
The ice machine remains off until enough ice is
removed from the storage bin to allow the sheet
of cubes to drop clear of the water curtain. As
the water curtain swings back to the operating
position, the bin switch closes and the ice
machine restarts.
WARNING
Disconnect electrical power to the entire ice
machine before proceeding.
2. Remove the fuse. Check the resistance across
the fuse with an ohm meter. Important
Reading Result
The water curtain must be ON (bin switch closed)
to start ice making.
Open (OL) Replace fuse
Specifications
Closed (O) Fuse is good The bin switch is a magnetically operated reed
switch. The magnet is attached to the lower right
corner of the water curtain. The switch is attached
to the evaporator mounting bracket.
The bin switch is connected to a varying D.C.
voltage circuit. (Voltage does not remain constant.)
NOTE: Because of a wide variation in D.C. voltage,
it is not recommended that a voltmeter be used to
check bin switch operation.

12
Electrical System
Check Procedure Water Curtain Removal Notes
1. Set the toggle switch to OFF. The water curtain must be on (bin switch closed) to
start ice making. While a freeze cycle is in progress,
the water curtain can be removed and installed at
any time without interfering with the electrical
control sequence.
2. Watch the bin switch light on the control board.
3. Move the water curtain toward the evaporator.
The bin switch must close. The bin switch light
“on” indicates the bin switch has closed
properly.
4. Move the water curtain away from the
evaporator. The bin switch must open. The bin
switch light “off” indicates the bin switch has
opened properly.
If the ice machine goes into harvest sequence while
the water curtain is removed, one of the following
will happen:
•Water curtain remains off
Ohm Test When the harvest cycle time reaches 3.5
minutes and the bin switch is not closed, the ice
machine stops as though the bin were full.
1. Disconnect the bin switch wires to isolate the
bin switch from the control board.
2. Connect an ohmmeter to the disconnected bin
switch wires. Set the ohmmeter to the 10,000
ohm scale.
•Water curtain is put back on
If the bin switch closes prior to reaching the 3.5
minute point, the ice machine immediately
returns to another freeze sequence prechill.
3. Cycle the bin switch by opening and closing the
water curtain.
4. With the bin switch open: Resistance readings
of more than 30,000 ohms indicate a correctly
operating bin switch.
5. With the bin switch closed: Resistance readings
of less than 70 ohms indicates a correctly
operating bin switch.
Important
Any reading between 70 and 30,000 ohms,
regardless of curtain position, indicates a
defective bin switch
0 OHMS
GOOD
GOOD
70 OHMS
SWITCH CLOSED
30,000 OHMS
SWITCH OPEN
INFINITE
OHMS
METER
READS
(OL)
BAD
Bin Switch Resistance Readings

13
Electrical System
COMPRESSOR ELECTRICAL
DIAGNOSTICS
The compressor will not start or will trip repeatedly
on overload.
Check Resistance (Ohm) Values
NOTE: Compressor windings can have very low
ohm values. Use a properly calibrated meter.
Perform the resistance test after the compressor
cools. The compressor dome should be cool enough
to touch (below 120°F/49°C) to assure that the
overload is closed and the resistance readings will
be accurate.
SINGLE PHASE COMPRESSORS
1. Disconnect power from the cuber and remove
the wires from the compressor terminals.
2. The resistance values must be within published
guidelines for the compressor. The resistance
values between C and S and between C and R,
when added together, should equal the
resistance value between S and R.
3. If the overload is open, there will be a resistance
reading between S and R, and open readings
between C and S and between C and R. Allow
the compressor to cool, then check the readings
again.
Check Motor Windings to Ground
Check continuity between all three terminals and
the compressor shell or copper refrigeration line.
Scrape metal surface to get good contact. If
continuity is present, the compressor windings are
grounded and the compressor should be replaced.
Determine if the Compressor is Seized
Check the amp draw while the compressor is trying
to start.
COMPRESSOR DRAWING LOCKED ROTOR
The two likely causes of this are:
•Defective starting component
•Mechanically seized compressor
To determine which you have:
1. Install high and low side gauges.
2. Try to start the compressor.
3. Watch the pressures closely.
A. If the pressures do not move, the compressor
is seized. Replace the compressor.
B. If the pressures move, the compressor is
turning slowly and is not seized. Check the
capacitors and start relay.
COMPRESSOR DRAWING HIGH AMPS
The continuous amperage draw on start-up should
not be near the maximum fuse size indicated on the
serial tag.
The voltage when the compressor is trying to start
must be within ±10% of the nameplate voltage.
Diagnosing Capacitors
•If the compressor attempts to start, or hums and
trips the overload protector, check the starting
components before replacing the compressor.
•Visual evidence of capacitor failure can include
a bulged terminal end or a ruptured membrane.
Do not assume a capacitor is good if no visual
evidence is present.
•A good test is to install a known good substitute
capacitor.
•Use a capacitor tester when checking a suspect
capacitor. Clip the bleed resistor off the
capacitor terminals before testing.
Diagnosing PTCR’s
See “PTCR Diagnostics” on the next page.

14
Electrical System
PTCR DIAGNOSTICS
What is a PTCR?
A PTCR (or Positive Temperature Coefficient
Resistor) is made from high-purity, semi-
conducting ceramics.
A PTCR is useful because of its resistance versus
temperature characteristic. The PTCR has a low
resistance over a wide (low) temperature range, but
upon reaching a certain higher temperature, its
resistance greatly increases, virtually stopping
current flow. When the source of heat is removed,
the PTCR returns to its initial base resistance.
In severe duty cycles, it can be used to repeatedly
switch (virtually stop) large currents at line
voltages.
PTCR’s have been used for many years in millions
of HVAC applications. In place of using the
conventional start relay/start capacitor, a simple
PTCR provides the starting torque assistance to
PSC (Permanent Split Capacitor) single-phase
compressors, which can equalize pressures before
starting.
Compressor Start Sequence
PTCR’s provide additional starting torque by
increasing the current in the auxiliary (start)
winding during starting. The PTCR is wired across
the run capacitor (in series with the start winding).
1. It is important for the refrigerant discharge and
suction pressures to be somewhat equalized
prior to the compressor starting. To assure
equalization of pressures the hot gas valve (and
HPR valve on remotes) will energize for 45
seconds prior to compressor starting. The hot
gas valve (and HPR valve on remotes) remains
on for an additional 5 seconds while the
compressor is starting.
2. When starting the compressor, the contactor
closes and the PTCR, which is at a low
resistance value, allows high starting current to
flow in the start winding.
3. The current passing through the PTCR causes it
to rapidly heat up, and after approximately .25-1
second it abruptly “switches” to a very high
resistance, virtually stopping current flow
through it.
4. At this point the motor is up to speed and all
current going through the start winding will now
pass through the run capacitor.
5. The PTCR remains hot and at a high resistance
as long as voltage remains on the circuit.
6. It is important to provide time between
compressor restarts to allow the PTCR to cool
down to near its initial temperature (low
resistance). When the contactor opens to stop
the compressor, the PTCR cools down to its
initial low resistance and is again ready to
provide starting torque assistance. To assure the
PTCR has cooled down, during an automatic
shut-off, the Q model ice machines have a built-
in 3-minute off time before it can restart.

15
Electrical System
Q-Model Automatic Shut-Off and Restart Troubleshooting PTCR’s
When the storage bin is full at the end of a harvest
cycle, the sheet of cubes fails to clear the water
curtain and will hold it open. After the water curtain
is held open for 7 seconds, the ice machine shuts
off. To assure the PTCR has cooled, the ice
machine remains off for 3 minutes before it can
automatically restart.
WHY A GOOD PTCR MAY FAIL
TO START THE COMPRESSOR
The PTCR must be cooled before attempting to start
the compressor, otherwise the high starting torque
may not last long enough.
For example, if the PTCR is properly cooled, say
60°F (15.6°C) when the compressor starts, it will
take .25 to 1.0 seconds before its temperature
reaches 260°F (126.6°C), and current flow is
stopped.
The ice machine remains off until enough ice has
been removed from the storage bin to allow the ice
to fall clear of the water curtain. As the water
curtain swings back to operating position, the bin
switch closes and the ice machine restarts, provided
the three-minute delay period is complete.
If the PTCR is still warm, say 160°F (71.1°C) when
the compressor starts, it will take only .125 to .50
seconds before its temperature reaches 260°F
(126.6°C), and current flow is stopped. This
decreased time may be insufficient to start the
compressor.
During Start-Up (First .25 - 1.0 Seconds)
SV1506
SV1507
L1 L2
CONTACTOR
CONTACTSC R
S
R R
COMPRESSOR
RUN CAPACITOR
L1 L2
CONTACTOR
CONTACTSC R
S
R R
COMPRESSOR
RUN CAPACITOR
PTCR
PTCR
A good PTCR may be too hot to operate properly at
start-up because:
•The ice machine’s 3-minute delay has been
overridden. Opening and closing the service
disconnect or cycling the toggle switch from
OFF to ICE will override the delay period.
•The control box temperature is too high.
Though rare, very high air temperatures (intense
sunlight, etc.) can greatly increase the
temperature of the control box and its contents.
This may require a longer off time to allow the
PTCR to cool.
•The compressor has short-cycled, or the
compressor overload has opened. Move the
toggle switch to OFF and allow the compressor
and PTCR to cool.
After Start-Up
(Current Flows Through Run Capacitor)
Continued on next page…

16
Electrical System
There are other problems that may cause
compressor start-up failure with a good PTCR in a
new, properly wired ice machine.
Room
Manitowoc
Part Number
Cera-Mite
Model Temperature
Resistance
Part Number
Q1800 8504913 305C9 8-22 Ohms
•The voltage at the compressor during start-up is
too low.
Manitowoc ice machines are rated at ±10% of
nameplate voltage at compressor start-up. (Ex:
An ice machine rated at 208-230 should have a
compressor start-up voltage between 187 and
253 volts.)
MEASURE OHMS BETWEEN
CENTER TAB AND END TAB
•The compressor discharge and suction pressures
are not matched closely enough or equalized.
These two pressures must be somewhat
equalized before attempting to start the
compressor. The hot gas valve (and HPR valve
on remotes) energizes for 45 seconds before the
compressor starts, and remains on 5 seconds
after the compressor starts. Make sure this is
occurring before assuming that the PTCR is
bad.
CHECKING THE PTCR
WARNING
Disconnect electrical power to the entire ice
machine at the building electrical disconnect box
before proceeding.
1. Visually inspect the PTCR. Check for signs of
physical damage.
NOTE: The PTCR case temperature may reach
210°F (100°C) while the compressor is running.
This is normal. Do not change a PTCR just because
it is hot.
2. Wait at least 10 minutes for the PTCR to cool to
room temperature.
3. Remove the PTCR from the ice machine.
4. Measure the resistance of the PTCR as shown
below. If the resistance falls outside of the
acceptable range, replace it.
LEAVE JUMPER
WIRE IN PLACE
SV1541
Manitowoc PTCR 8504913