Page 1
Marine
Q800
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 80-1216-3
2/2001
Page 2
Safety Notices
Procedural 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.
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 troublefree 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.
Page 3
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 – Q800 - 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
Diagnosing Ice Machine That Will Not Run..........................................................................................23
Page 4
Table of Contents (cont.)
Refrigeration System
Sequence of Operation
Self-Contained Water-Cooled Models.........................................................................................................25
Operational Analysis (Diagnostics)
General............................................................................................................................................................27
Before Beginning Service ..............................................................................................................................28
Ice Production Check ....................................................................................................................................28
Installation/Visual Inspection Checklist......................................................................................................29
Water System Checklist ................................................................................................................................29
Ice Formation Pattern ...................................................................................................................................30
Safety Limits...................................................................................................................................................32
Comparing Evaporator Inlet and Outlet Temperatures............................................................................35
Hot Gas Valve Temperature Check.............................................................................................................36
Analyzing Discharge Pressure During Freeze or Harvest Cycle
Procedure..................................................................................................................................................37
Freeze Cycle Discharge Pressure High Checklist.................................................................................37
Freeze Cycle Discharge Pressure Low Checklist..................................................................................37
Analyzing Suction Pressure During Freeze Cycle
Procedure..................................................................................................................................................38
Freeze Cycle Suction Pressure High Checklist .....................................................................................39
Freeze Cycle Suction Pressure Low Checklist......................................................................................39
How to Use the Refrigeration System Operational Analysis Tables.........................................................40
Refrigeration System Operational Analysis Table
Single TXV................................................................................................................................................41
Pressure Control Specifications and Diagnostics
High Pressure Cutout (HPCO) Control.......................................................................................................42
Cycle Time/24 Hour Ice Production/Refrigerant Pressure Charts
Q800 ................................................................................................................................................................43
Refrigerant Recovery/Evacuating and Recharging
Normal Self-Contained Model Procedures..................................................................................................44
System Contamination Cleanup...................................................................................................................45
Replacing Pressure Controls Without Removing Refrigerant Charge ....................................................48
Filter-Driers....................................................................................................................................................50
Total System Refrigerant Charges...............................................................................................................50
Refrigerant Definitions..................................................................................................................................51
Refrigerant Re-Use Policy.............................................................................................................................52
HFC Refrigerant Questions and Answers...................................................................................................53
Page 5
Electrical System
Energized Parts Charts
SELF-CONTAINED WATER-COOLED MODELS
Ice Making Control Board Relays
Sequence
Of
Operation
Start-Up
1. Water Purge
2. Refrigeration System
1
Start-Up
Freeze Sequence
3. Pre-Chill
Freeze
Harvest Sequence
5. Water Purge
6. Harvest
7. Automatic
Shut-Off
1
Initial 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:
1 2 3 4 5 5A Length
Water
Pump
On
Off
Off
On
On
Off
Off
Hot Gas
Valve(s)
On
On
Off
Off
On
On
Off
Electrical System
Water
Dump
Valve
On
Off
Off
Off
On
Off
Off
Contactor
Coil
Off
On
On
On
On
On
Off
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).
Compressor
Off
On
On
On
On
On
Off
Of
Time
45 Seconds
5 Seconds
30 Seconds
Until 7 sec. water
contact with ice
thickness probe
Factory-set at
45 Seconds
Bin switch
activation
Until bin switch
re-closes
1
Page 6
Electrical System
T
Wiring Diagram Sequence of Operation
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).
L1
TB35
TB35
TB32
HIGH PRES
CUTOUT
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
CONTACTOR
CONTACTS
(42)
L1
TB33
(64)
(66)
(51)
(55)
BIN SWITCH
(52)
(62)
(63)
(65)
*OVERLOAD
(48)
R
(85) (86)
FAN CYCLE CONTROL
2
4
1
3
5
TRANS.
1C
1F
1G
C
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
(68)
(69)
(62)
(49)
(47)
(53)
TB34
RUN CAPACITOR**
SEE SERIAL PLATE FOR VOLTAGE
(61)
(60)
(58)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
ICE
OFF
CLEAN
RUN CAPACITOR
(46) (50)
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
(57)
TB31
TB37
(59)
(73)
(56)
TOGGLE SWITCH
INTERNAL WORKING
VIEW
R
(45)
PTCR
FAN MOTOR
(AIR COOLED ONLY)
(98)
TERMINATES AT
PIN CONNECTION
CONTACTOR
COIL
VIEW FOR WIRING
R
66
62
(22)
(80)
(81)
WATER
PUMP
L2 (N)
(75)
(99)
(74)
68
67
69
SV1646-1
TB30
TB30
TB30
TB30
B30
TB30
Self-Contained Models
1. Water Purge (45 Seconds)
Toggle Switch
Bin Switch
Control Board Relays
#1 Water Pump Closed / ON
#2
#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
ICE
Closed
2
Page 7
T
Initial Start-Up Or Start-Up After Automatic Shut-Off (cont.)
2. REFRIGERATION SYSTEM
START-UP
The compressor starts after the 45second water purge, and it remains on
throughout the Freeze and Harvest
cycles.
The hot gas valve(s) remains on for
the first 5 seconds of the initial
compressor start-up.
L1
TB35
TB35
TB32
HIGH PRES
CUTOUT
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
CONTACTOR
CONTACTS
(42)
L1
TB33
(64)
(66)
(51)
(55)
BIN SWITCH
(52)
(62)
(63)
(65)
*OVERLOAD
(48)
R
(85) (86)
FAN CYCLE CONTROL
2
4
1
3
5
TRANS.
1C
1F
1G
C
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
(68)
(62)
(53)
RUN CAPACITOR**
Self-Contained Models
2. Refrigeration System Start-Up (5 Seconds)
Toggle Switch
Bin Switch
Control Board Relays
#1 Water Pump Open / OFF
#2
#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
ICE
Closed
Electrical System
(61)
(60)
(57)
(58)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
TOGGLE SWITCH
ICE
(69)
INTERNAL WORKING
OFF
VIEW
CLEAN
(49)
RUN CAPACITOR
(47)
(46) (50)
PTCR
TB34
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
TB31
TB37
(59)
(73)
(56)
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
(98)
TERMINATES AT
PIN CONNECTION
CONTACTOR
COIL
VIEW FOR WIRING
R
(80)
66
62
(22)
(81)
WATER
PUMP
L2 (N)
(75)
(99)
(74)
68
67
69
SV1646-2
TB30
TB30
TB30
TB30
B30
TB30
3
Page 8
Electrical System
T
Freeze Sequence
3. PRE-CHILL
To pre-chill the evaporator, the compressor
runs for 30 seconds prior to water flow.
L1
TB35
TB35
TB32
HIGH PRES
CUTOUT
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
CONTACTOR
CONTACTS
(42)
L1
TB33
(64)
(66)
(51)
(55)
BIN SWITCH
(52)
(62)
(63)
(65)
*OVERLOAD
(48)
R
(85) (86)
FAN CYCLE CONTROL
2
4
1
3
5
TRANS.
1C
1F
1G
C
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
RUN CAPACITOR**
Self-Contained Models
3. Pre-Chill (30 Seconds)
Toggle Switch
Bin Switch
Control Board Relays
#1 Water Pump Open / OFF
#2
#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
ICE
Closed
(53)
(61)
(60)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
(68)
ICE
(69)
OFF
CLEAN
(62)
(49)
RUN CAPACITOR
(47)
TB34
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
(57)
(58)
TOGGLE SWITCH
INTERNAL WORKING
VIEW
(46) (50)
PTCR
(98)
TB31
TB37
(59)
TERMINATES AT
PIN CONNECTION
(73)
(56)
R
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
CONTACTOR
COIL
VIEW FOR WIRING
66
62
(22)
(80)
(81)
WATER
PUMP
(99)
(74)
68
67
(75)
69
L2 (N)
TB30
TB30
TB30
TB30
B30
TB30
4
Page 9
T
Freeze Sequence (cont.)
4. FREEZE
The water pump starts after the 30second pre-chill. An even flow of
water is directed across the evaporator
and into each cube cell, where it
freezes.
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 6minute freeze lock has expired.
Self-Contained Models
Electrical System
L1
(55)
TB35
TB35
TB32
HIGH PRES
CUTOUT
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
CONTACTOR
CONTACTS
(42)
L1
TB33
(64)
(66)
(51)
BIN SWITCH
(52)
(62)
(63)
(65)
*OVERLOAD
(48)
R
(85) (86)
FAN CYCLE CONTROL
2
4
1
3
5
TRANS.
1C
1F
1G
C
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
RUN CAPACITOR**
(53)
(61)
(60)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
(68)
ICE
(69)
OFF
CLEAN
(62)
(49)
(47)
TB34
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
(57)
(58)
TOGGLE SWITCH
INTERNAL WORKING
VIEW
RUN CAPACITOR
(46) (50)
PTCR
(98)
TB31
TB37
(59)
TERMINATES AT
PIN CONNECTION
(73)
(56)
R
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
CONTACTOR
COIL
VIEW FOR WIRING
66
62
(22)
(80)
(81)
WATER
PUMP
L2 (N)
(75)
(99)
(74)
68
67
69
SV1646-4
TB30
TB30
TB30
TB30
B30
TB30
4. Freeze (Until 7 Seconds of Water Contact with Ice Thickness Probe)
Toggle Switch
Bin Switch
ICE
Closed
Control Board Relays
#1 Water Pump Closed / ON
#2
#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
Page 10
Electrical System
T
2
4
1
3
5
TRANS.
FUSE (7A)
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.
After the 45 second water purge, the
water pump and dump valve de-
L1
(55)
TB35
HIGH PRES
CUTOUT
TB32
energize. The hot gas valve also
opens at the beginning of the water
purge to divert hot refrigerant gas into
the evaporator.
TB35
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
(64)
(66)
CONTACTOR
CONTACTS
(42)
L1
(51)
TB33
BIN SWITCH
*OVERLOAD
(48)
(52)
FAN CYCLE CONTROL
1C
1F
1G
(62)
(63)
(65)
R
C
(85) (86)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
(53)
RUN CAPACITOR**
Self-Contained Models
5. Water Purge (45 Seconds)
Toggle Switch
Bin Switch
ICE
Closed
Control Board Relays
#1 Water Pump Closed / ON
#2
#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
(61)
(60)
(58)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
(68)
(69)
(62)
TOGGLE SWITCH
ICE
INTERNAL WORKING
OFF
VIEW
CLEAN
(49)
RUN CAPACITOR
(47)
(46) (50)
PTCR
TB34
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
(57)
(98)
TB31
TB37
(59)
TERMINATES AT
PIN CONNECTION
(73)
(56)
R
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
CONTACTOR
COIL
VIEW FOR WIRING
66
62
(22)
(80)
(81)
WATER
PUMP
L2 (N)
(75)
(99)
(74)
68
67
69
SV1646-5
TB30
TB30
TB30
TB30
B30
TB30
6
Page 11
T
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.
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).
L1
TB35
TB35
TB32
HIGH PRES
CUTOUT
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
CONTACTOR
CONTACTS
(42)
L1
TB33
(64)
(66)
(51)
(55)
BIN SWITCH
(52)
(62)
(63)
(65)
*OVERLOAD
(48)
R
(85) (86)
FAN CYCLE CONTROL
2
4
1
3
5
TRANS.
1C
1F
1G
C
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
(68)
(62)
(53)
RUN CAPACITOR**
Self-Contained Models
6. Harvest (Until Bin Switch Activation)
Toggle Switch
Bin Switch
Control Board Relays
#1 Water Pump Open / OFF
#2
#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
ICE
Closed
Electrical System
(61)
(60)
(57)
(58)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
TOGGLE SWITCH
ICE
(69)
INTERNAL WORKING
OFF
VIEW
CLEAN
(49)
RUN CAPACITOR
(47)
(46) (50)
PTCR
TB34
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
TB31
TB37
(59)
(73)
(56)
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
(98)
TERMINATES AT
PIN CONNECTION
CONTACTOR
COIL
VIEW FOR WIRING
R
(80)
66
62
(22)
(81)
WATER
PUMP
L2 (N)
(75)
(99)
(74)
68
67
69
SV1646-6
TB30
TB30
TB30
TB30
B30
TB30
7
Page 12
Electrical System
T
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.
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
L1
TB35
TB32
HIGH PRES
CUTOUT
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
(64)
(66)
(55)
BIN SWITCH
(62)
(63)
(65)
2
4
1
3
5
TRANS.
1C
1F
1G
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
off for 3 minutes before it can
automatically restart.
TB35
(42)
CONTACTOR
CONTACTS
L1
TB33
(51)
(52)
*OVERLOAD
(48)
(85)
FAN CYCLE CONTROL
R
C
(86)
COMPRESSOR
S
RUN CAPACITOR**
Self-Contained Models
7. Automatic Shut-Off (Until Bin Switch Closes)
Toggle Switch
Bin Switch
ICE
Open
Control Board Relays
#1 Water Pump Open / OFF
#2
#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
(53)
(61)
(60)
(58)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
(68)
(69)
(62)
TOGGLE SWITCH
ICE
INTERNAL WORKING
OFF
VIEW
CLEAN
(49)
RUN CAPACITOR
(47)
(46) (50)
PTCR
TB34
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
(57)
(98)
TB31
TB37
(59)
TERMINATES AT
PIN CONNECTION
(73)
(56)
R
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
CONTACTOR
COIL
VIEW FOR WIRING
66
62
(22)
(80)
(81)
WATER
PUMP
L2 (N)
(75)
(99)
(74)
68
67
69
SV1646-7
TB30
TB30
TB30
TB30
B30
TB30
8
Page 13
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)
9
Page 14
Electrical System
(62) (63) (64) (65) (66) (66)
(67)
(68)
(69)
(62)
(74)
(55) (61)
(60)
(77)
(76)
(80) (75)
(98)
(57)
(99)
(81)
(58)
(59)
(73)
(56)
A
(7A)
(21)
(22)
V
(49)
(48)
(47)
(42)
(50)
(45)
(46)
Q800 - 1 PHASE
L1
CAUTION: DISCONNECT POWER BEFORE
WORKING ON ELECTRICAL CIRCUITRY.
NOTE: DIAGRAM SHOWN DURING FREEZE CYCLE.
SEE SERIAL PLATE FOR VOLTAGE
L2 (N)
TB
35
HIGH
PRESSURE
CUT-OUT
ICE THICKNESS PROBE
TB32
WATER LEVEL PROBE
NOT USED
BIN SWITCH
WATER
ALVE
2
4
1
3
5
TR
1C
1F
1G
NS.
FUSE
LOW D.C.
VOLTAGE
PLUG
TOGGLE SWITCH
CLEAN LIGHT
WATER LEVEL LIGHT
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
ICE
OFF
CLEAN
TB31
TB37
← INTERNAL
WORKING VIEW
HOT GAS
SOLENOID
DUMP
SOLENOID
PIN CONNECTION
TERMINATES AT
CONTACTOR
COIL
WATER
PUMP
VIEW FOR WIRING
68
66
62
67
69
TB30
TB30
TB30
TB30
TB35
10
CONTACTOR
CONTACTS
L1
*OVERLOAD
COMPRESSOR
SR
C
RUN CAPACITOR
RR
TB30
PTCR
SV1646
Page 15
Component Specifications and Diagnostics
MAIN FUSE
Function
The control board fuse stops ice machine operation
if electrical components fail causing high amp
draw.
Specifications
The main fuse is 250 Volt, 7 amp.
Check Procedure
WARNING
High (line) voltage is applied to the control board
BIN SWITCH
Function
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
2. Automatic ice machine shut-off.
(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.
1. If the bin switch light is on with the water
curtain closed, the fuse is good.
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.
Reading Result
Open (OL) Replace fuse
Closed (O) Fuse is good
The water curtain must be ON (bin switch closed)
to start ice making.
Specifications
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.
Electrical System
ice machine to the freeze cycle.
This occurs when the bin switch is opened and
closed again within 7 seconds during the harvest
cycle.
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.
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.
Important
11
Page 16
Electrical System
Check Procedure
1. Set the toggle switch to OFF.
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.
Ohm Test
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.
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
Water Curtain Removal Notes
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.
If the ice machine goes into harvest sequence while
the water curtain is removed, one of the following
will happen:
• Water curtain remains off
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.
• 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.
12
30,000 OHMS
SWITCH OPEN
70 OHMS
SWITCH CLOSED
0 OHMS
GOOD
BAD
Bin Switch Resistance Readings
GOOD
INFINITE
OHMS
METER
READS
(OL)
Page 17
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.
Electrical System
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.
13
Page 18
Electrical System
PTCR DIAGNOSTICS
What is a PTCR?
A PTCR (or Positive Temperature Coefficient
Resistor) is made from high-purity, semiconducting 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 builtin 3-minute off time before it can restart.
14
Page 19
Q-Model Automatic Shut-Off and Restart
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.
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.
L1 L2
CONTACTOR
CONTACTS
C
COMPRESSOR
R
S
RUN CAPACITOR
R R
PTCR
SV1506
During Start-Up (First .25 - 1.0 Seconds)
L1 L2
CONTACTOR
CONTACTS
C
COMPRESSOR
R
RUN CAPACITOR
R R
S
PTCR
SV1507
After Start-Up
(Current Flows Through Run Capacitor)
Electrical System
Troubleshooting PTCR’s
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.
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.
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.
Continued on next page…
15
Page 20
Electrical System
There are other problems that may cause
compressor start-up failure with a good PTCR in a
new, properly wired ice machine.
• 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.)
• 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.
Model
Q800 8504993 305C19 18-40 Ohms
Manitowoc
Part Number
Cera-Mite
Part Number
Room
Temperature
Resistance
MEASURE OHMS BETWEEN
CENTER TAB AND END TAB
LEAVE JUMPER
WIRE IN PLACE
SV1541
Manitowoc PTCR 8504913
16
Page 21
ICE/OFF/CLEAN TOGGLE SWITCH
Function
The switch is used to place the ice machine in ICE,
OFF or CLEAN mode of operation.
Electrical System
CONTROL BOARD RELAYS
Function
The control board relays energize and de-energize
system components.
Specifications
Double-pole, double-throw switch. The switch is
connected into a varying low D.C. voltage circuit.
Check Procedure
NOTE: Because of a wide variation in D.C. voltage,
it is not recommended that a volt meter be used to
check toggle switch operation.
1. Inspect the toggle switch for correct wiring.
2. Isolate the toggle switch by disconnecting all
wires from the switch, or by disconnecting the
Molex connector and removing wire #69 from
the toggle switch.
3. Check across the toggle switch terminals using a
calibrated ohm meter. Note where the wire
numbers are connected to the switch terminals,
or refer to the wiring diagram to take proper
readings.
Switch Setting Terminals Ohm Reading
66-62 Open
ICE 67-68 Closed
67-69 Open
66-62 Closed
CLEAN 67-68 Open
67-69 Closed
66-62 Open
OFF 67-68 Open
67-69 Open
4. Replace the toggle switch if ohm readings do
not match all three switch settings.
Specifications
Relays are not field replaceable. There are five
relays on the control board:
Relay
#1 Water Pump
#2
#3 Hot Gas V alve
#4 Water Dump Valve
#5 Contactor (Self-Contained)
Contactor / Liquid Line Solenoid (Remotes)
Controls
17
Page 22
Electrical System
ELECTRONIC CONTROL BOARD
AC LINE VOLTAGE
ELECTRICAL PLUG
(NUMBERS MARKED ON
WIRES)
MAIN FUSE (7A)
AUTOMATIC CLEANING
SYSTEM (AuCS)
ACCESSORY PLUG
60
61
20
56
57
58
55
L1 PRIMARY
POWER SUPPLY
N 115V
L2 208-230V
CLEAN LIGHT
YELLOW
NOT USED
BIN SWITCH LIGHT
GREEN
HARVEST LIGHT/
SAFETY LIMIT
CODE LIGHT
RED
(3/16” CONNECTION)
ICE THICKNESS
PROBE
NOT USED
NOT USED
DC LOW VOLTAGE
ELECTRICAL PLUG
(NUMBERS MARKED
ON WIRES)
67
62
63
1C
1F
1G
68
65
Control Board
SV1588
18
Page 23
General
Q-Model control boards use a dual voltage
transformer. This means only one control board is
needed for both 115V and 208-230V use.
Safety Limits
In addition to standard safety controls, such as the
high pressure cut-out, the control board has built-in
safety limits.
These safety limits protect the ice machine from
major component failures. For more information,
see “Safety Limits”.
Electrical System
Inputs
The control board, along with inputs, controls all
electrical components, including the ice machine
sequence of operation. Prior to diagnosing, you
must understand how the inputs affect the control
board operation.
Refer to specific component specifications (inputs),
wiring diagrams and ice machine sequence of
operation sections for details.
As an example, refer to “Ice Thickness Probe” in
the component specifications section of this manual
for information relating to how the probe and
control board function together.
This section will include items such as:
• How a harvest cycle is initiated
• How the harvest light functions with the probe
• Freeze time lock-in feature
• Maximum freeze time
• Diagnosing ice thickness control circuitry
19
Page 24
Electrical System
Ice Thickness Probe (Harvest Initiation)
HOW THE PROBE WORKS
Manitowoc’s electronic sensing circuit does not rely
on refrigerant pressure, evaporator temperature,
water levels or timers to produce consistent ice
formation.
As ice forms on the evaporator, water (not ice)
contacts the ice thickness probe. After the water
completes this circuit across the probe continuously
for 6-10 seconds, a harvest cycle is initiated.
SV1729A
Ice Thickness Probe
To allow the service technician to initiate a harvest
cycle without delay, this feature is not used on the
first cycle after moving the toggle switch OFF and
back to ICE.
MAXIMUM FREEZE TIME
The control system includes a built-in safety which
will automatically cycle the ice machine into
harvest after 60 minutes in the freeze cycle.
ICE THICKNESS CHECK
The ice thickness probe is factory-set to maintain
the ice bridge thickness at 1/8” (3.2 mm).
NOTE: Make sure the water curtain is in place
when performing this check. It prevents water from
splashing out of the water trough.
1. Inspect the bridge connecting the cubes. It
should be about 1/8” (3.2 mm) thick.
2. If adjustment is necessary, turn the ice thickness
probe adjustment screw clockwise to increase
bridge thickness, or counterclockwise to
decrease bridge thickness.
HARVEST/SAFETY LIMIT LIGHT
This light’s primary function is to be on as water
contacts the ice thickness probe during the freeze
cycle, and remain on throughout the entire harvest
cycle. The light will flicker as water splashes on the
probes.
The light’s secondary function is to continuously
flash when the ice machine is shut off on a safety
limit, and to indicate which safety limit shut off the
ice machine.
FREEZE TIME LOCK-IN FEATURE
The ice machine control system incorporates a
freeze time lock-in feature. This prevents the ice
machine from short cycling in and out of harvest.
The control board locks the ice machine in the
freeze cycle for six minutes. If water contacts the
ice thickness probe during these six minutes, the
harvest light will come on (to indicate that water is
in contact with the probe), but the ice machine will
stay in the freeze cycle. After the six minutes are
up, a harvest cycle is initiated. This is important to
remember when performing diagnostic procedures
on the ice thickness control circuitry.
NOTE: Turning the adjustment 1/3 of a turn will
change the ice thickness about 1/16” (1.5 mm).
ADJUSTING
SCREW
1/8” (3.2MM)
ICE
THICKNESS
SV1208
Ice Thickness Check
Make sure the ice thickness probe wire and the
bracket do not restrict movement of the probe.
20
Page 25
A
Electrical System
DIAGNOSING ICE THICKNESS CONTROL CIRCUITRY
Ice Machine Does Not Cycle Into Harvest when Water Contacts the Ice Thickness Control Probe
Step 1 Bypass the freeze time lock-in feature by moving the ICE/OFF/CLEAN switch to OFF and back to
ICE. Wait until the water starts to flow over the evaporator.
Step 2 Clip the jumper wire leads to the ice thickness probe and any cabinet ground.
ICE THICKNESS PROBE
CLEAN LIGHT
WATER LEVEL LIGHT
EVAPORATOR
1C
HARVEST/SAFETY LIMIT LIGHT
SV1592G
SV1588
Step 2
Step 2 Jumper wire connected from probe to ground
Monitoring of Harvest Light Correction
The harvest light comes on, and 6-10 seconds later,
ice machine cycles from freeze to harvest.
The harvest light comes on but the ice machine
stays in the freeze sequence.
The ice thickness control circuitry is functioning
properly. Do not change any parts.
The ice thickness control circuitry is functioning
properly. The ice machine is in a six-minute freeze
time lock-in. Verify step 1 of this procedure was
followed correctly.
The harvest light does not come on. Proceed to Step 3, below.
Step 3 Disconnect the ice thickness probe from the control board at terminal 1C. Clip the jumper wire leads
to terminal 1C on the control board and any cabinet ground. Monitor the harvest light.
ICE THICKNESS PROBE
GROUND
JUMPER WIRE
CLEAN LIGHT
WATER LEVEL LIGHT
EVAPORATOR
1C
HARVEST/SAFETY LIMIT LIGHT
SV1591G
SV1588G
Step 3
Step 3 Jumper wire connected from control board terminal 1C to ground
Monitoring of Harvest Light Correction
The harvest light comes on, and 6-10 seconds later,
ice machine cycles from freeze to harvest.
The harvest light comes on but the ice machine
stays in the freeze sequence.
The harvest light does not come on. The control board is causing the malfunction.
The ice thickness probe is causing the malfunction.
The control circuitry is functioning properly. The ice
machine is in a six-minute freeze time lock-in (verify
step 1 of this procedure was followed correctly).
21
Page 26
Electrical System
Ice Machine Cycles Into Harvest Before Water Contact With The Ice Thickness Probe
Step 1 Disconnect the ice thickness probe from the control board at terminal 1C.
Step 2 Bypass the freeze time lock-in feature by moving the ICE/OFF/CLEAN switch to OFF and back to
ICE. Wait until the water starts to flow over the evaporator, then monitor the harvest light.
ICE THICKNESS PROBE
CLEAN LIGHT
WATER LEVEL LIGHT
EVAPORATOR
1C
HARVEST/SAFETY LIMIT LIGHT
SV1591G
SV1588G
Step 2
Step 2 Disconnect probe from control board terminal 1C
Monitoring of Harvest Light Correction
The harvest light stays off and the ice machine
remains in the freeze sequence.
The ice thickness probe is causing the malfunction.
Verify that the Ice Thickness probe is adjusted
correctly.
The harvest light comes on, and 6-10 seconds later,
The control board is causing the malfunction.
the ice machine cycles from freeze to harvest.
22
Page 27
Electrical System
Diagnosing Ice Machine That Will Not Run
WARNING
High (line) voltage is applied to the control board
(terminals #55 and #56) at all times. Removing
control board fuse or moving the toggle switch to
OFF will not remove the power supplied to the
control board.
Step Check Notes
1 Verify primary voltage supply to ice
machine.
2 Verify the high-pressure cutout is
closed.
3 Verify control board fuse is OK. If the bin switch light functions, the fuse is OK.
4 Verify the bin switch functions properly. A defective bin switch can falsely indicate a full bin of ice.
5 Verify ICE/OFF/CLEAN toggle switch
functions properly.
6 Verify low DC voltage is properly
grounded.
7 Replace the control board. Be sure Steps 1-6 were followed thoroughly. Intermittent
L1
Q0420/Q0450/Q0600/Q0800/Q1000 ICE MACHINES
SELF-CONTAINED 1 PHASE
CAUTION: DISCONNECT POWER BEFORE WORKING
ON ELECTRICAL CIRCUITRY.
DIAGRAM SHOWN DURING FREEZE CYCLE
(55)
TB35
HIGH PRES
CUTOUT
TB32
2
3
ICE THICKNESS PROBE
WATER LEVEL PROBE
NOT USED
4
(64)
6
(66)
BIN SWITCH
5
(42)
CONTACTOR
CONTACTS
L1
TB33
TB35
(51)
*OVERLOAD
(48)
(52)
FAN CYCLE CONTROL
Verify that the fuse or circuit breaker is closed.
The H.P.C.O. is closed if primary power voltage is present
at terminals #55 and #56 on the control board.
A defective toggle switch may keep the ice machine in
the OFF mode.
Loose DC wire connections may intermittently stop the ice
machine.
problems are not usually related to the control board.
2
4
1
3
5
TRANS.
1C
1F
1G
(62)
(63)
(65)
R
C
(85) (86)
1
FUSE (7A)
LOW D.C.
VOLTAGE
PLUG
(67)
(66)
COMPRESSOR
S
(53)
RUN CAPACITOR**
(61)
(60)
(58)
CLEAN LIGHT
WATER LEVEL
BIN SWITCH LIGHT
HARVEST LIGHT/
SAFETY LIMIT CODE LIGHT
(68)
(69)
(62)
TB34
TOGGLE SWITCH
ICE
INTERNAL WORKING
OFF
VIEW
CLEAN
(49)
RUN CAPACITOR
(47)
(46) (50)
PTCR
SEE SERIAL PLATE FOR VOLTAGE
(21)
WATER
VALVE
(77)
HOT GAS
SOLENOID
(76)
DUMP
SOLENOID
(57)
(98)
TB31
TB37
(59)
TERMINATES AT
PIN CONNECTION
(73)
(56)
R
R
(45)
FAN MOTOR
(AIR COOLED ONLY)
CONTACTOR
COIL
VIEW FOR WIRING
(22)
(80)
(81)
66
62
WATER
PUMP
(99)
(74)
68
67
(75)
69
L2 (N)
TB30
TB30
TB30
TB30
TB30
TB30
23
Page 28
Electrical System
24
Page 29
Q
Sequence of Operation
WATER-COOLED MODELS
HEAT
EXCHANGER
Refrigeration System
EXPANSION
VALVE
HOT GAS
SOLENOID VALVE
Electrical System
EVAPORATOR
COMPRESSOR
DRIER
RECEIVER
HIGH PRESSURE VAPOR
HIGH PRESSURE LI
UID LOW PRESSURE LIQUID LOW PRESSURE VAPOR
Self-Contained Prechill and Freeze Cycle
Prechill Refrigeration Sequence
No water flows over the evaporator during the
prechill. The refrigerant absorbs heat (picked up
during the harvest cycle) from the evaporator. The
suction pressure decreases during the prechill.
AIR OR WATER
STRAINER
CONDENSER
SV1569
Freeze Cycle Refrigeration Sequence
The refrigerant absorbs heat from water running
over the evaporator surface. The suction pressure
gradually drops as ice forms.
25
Page 30
Refrigeration System
HEAT
EXCHANGER
EXPANSION
VALVE
HOT GAS
SOLENOID VALVE
EVAPORATOR
COMPRESSOR
DRIER
RECEIVER
HIGH PRESSURE VAPOR HIGH PRESSURE LIQUID LOW PRESSURE LIQUID LOW PRESSURE VAPOR
Self-Contained Harvest Cycle
Harvest Cycle Refrigeration Sequence
Hot gas flows through the energized hot gas valve,
heating the evaporator. The hot gas valve is sized to
allow the proper amount of refrigerant into the
evaporator. This specific sizing (along with the
WATER
STRAINER
CONDENSER
SV1570
proper system refrigerant charge) assures proper
heat transfer, without the refrigerant condensing and
slugging the compressor.
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Operational Analysis (Diagnostics)
GENERAL
When analyzing the refrigeration system, it is
important to understand that different refrigeration
component malfunctions may cause very similar
symptoms.
Also, many external factors can make good
refrigeration components appear bad. These factors
can include improper installation, or water system
malfunctions such as hot incoming water supply or
water loss.
The following two examples illustrate how similar
symptoms can result in a misdiagnosis.
1. An expansion valve bulb that is not securely
fastened to the suction line and/or not insulated
will cause a good expansion valve to flood. If a
service technician fails to check for proper
expansion valve bulb mounting, he may replace
the expansion valve in error.
The ice machine now functions normally. The
technician erroneously thinks that the problem
was properly diagnosed and corrected by
replacing the expansion valve. Actually, the
problem (loose bulb) was corrected when the
technician properly mounted the bulb of the
replacement expansion valve.
Refrigeration System
3. An ice machine that is low on charge may cause
a good expansion valve to starve. If a service
technician fails to verify the system charge, he
may replace the expansion valve in error.
During the replacement procedure, recovery,
evacuation and recharging are performed
correctly. The ice machine now functions
normally. The technician erroneously thinks that
the problem was properly diagnosed and
corrected by replacing the expansion valve.
The service technician’s failure to check the ice
machine for a low charge condition resulted in a
misdiagnosis and the needless replacement of a
good expansion valve.
When analyzing the refrigeration system, use the
Refrigeration System Operational Analysis Table.
This table, along with detailed checklists and
references, will help prevent replacing good
refrigeration components due to external problems.
The service technician’s failure to check the
expansion valve bulb for proper mounting (an
external check) resulted in a misdiagnosis and
the needless replacement of a good expansion
valve.
27
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Refrigeration System
BEFORE BEGINNING SERVICE
Ice machines may experience operational problems
only during certain times of the day or night. A
machine may function properly while it is being
serviced, but malfunctions later. Information
provided by the user can help the technician start in
the right direction, and may be a determining factor
in the final diagnosis.
Ask these questions before beginning service:
• When does the ice machine malfunction? (night,
day, all the time, only during the freeze cycle,
etc.)
• When do you notice low ice production? (one
day a week, every day, on weekends, etc.)
• Can you describe exactly what the ice machine
seems to be doing?
• Has anyone been working on the ice machine?
• Is anything (such as boxes) usually stored near
or on the ice machine which could obstruct
airflow around the machine?
• During “store shutdown,” is the circuit breaker,
water supply or air temperature altered?
• Is there any reason why incoming water
pressure might rise or drop substantially?
ICE PRODUCTION CHECK
The amount of ice a machine produces directly
relates to the operating water and air temperatures.
This means an ice machine in a 70°F (21.2°C) room
with 50°F (10.0°C) water produces more ice than
the same model ice machine in a 90°F (32.2°C)
room with 70°F (21.2°C) water.
1. Determine the ice machine operating conditions:
Air temp. entering condenser: ____°
Air temp. around ice machine: ____°
Water temp. entering sump trough: ____°
2. Refer to the appropriate 24 Hour Ice Production
Chart. Use the operating conditions determined
in Step 1 to find published 24 hour ice
production: ______
3. Perform an actual ice production check. Use the
formula below.
1. __________ + __________ =
Freeze Time Harvest Time Total Cycle Time
2.
3. __________ x __________ =
1440 ÷ __________ =
Minutes in 24 Hours Total Cycle Time Cycles Per Day
Weight of One Harvest Cycles Per Day Actual 24 Hour Ice Production
__________
__________
__________
Important
• Times are in minutes.
Example: 1 min., 15 sec. converts to 1.25 min.
(15 seconds ÷ 60 seconds = .25 minutes)
• Weights are in pounds.
Example: 2 lb., 6 oz. converts to 2.375 lb.
(6 oz. ÷16 oz. = .375 lb.)
• Weighing the ice is the only 100% accurate
check. However, if the ice pattern is normal
and the 1/8” thickness is maintained, the ice
slab weights listed with the 24 Hour Ice
Production Charts may be used.
4. Compare the results of Step 3 with Step 2. Ice
production is normal when these numbers match
closely. If they match closely, determine if:
• another ice machine is required.
• more storage capacity is required.
• relocating the existing equipment to lower
the load conditions is required.
Contact the local Manitowoc distributor for
information on available options and
accessories.
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Page 33
INSTALLATION/VISUAL INSPECTION CHECKLIST
Possible Problem Corrective Action
Ice machine is not level Level the ice machine
Improper clearance
around top, sides and/or
back of ice machine
Ice machine is not on an
independent electrical
circuit
Water filtration is
plugged (if used)
Water drains are not run
separately and/or are
not vented
Reinstall according to
the Installation M anual
Reinstall according to
the Installation M anual
Install a new water filter
Run and vent drains
according to the
Installation Manual
Refrigeration System
WATER SYSTEM CHECKLIST
A water-related problem often causes the same
symptoms as a refrigeration system component
malfunction.
Example: A water dump valve leaking during the
freeze cycle, a system low on charge, and a starving
TXV have similar symptoms.
Water system problems must be identified and
eliminated prior to replacing refrigeration
components.
Possible Problem Corrective Action
Water area (evaporator)
is dirty
Water inlet pressure not
between 20 and 80 psi
Incoming water
temperature is not
between 35°F (1.7°C) and
90°F (32.2°C).
Water filtration is plugged
(if used)
Water dump valve
leaking during the freeze
cycle
Vent tube is not installed
on water outlet drain
Hoses, fittings, etc., are
leaking water
Water fill valve is stuck
open
Water is spraying out of
the sump trough area
Uneven water flow across
the evaporator
Water is freezing behind
the evaporator
Plastic extrusions and
gaskets are not secured
to the evaporator
Water does not flow over
the evaporator (not
trickle) immediately after
the prechill
Clean as needed
Install a water
regulator valve or
increase the water
pressure
If too hot, check the
hot water line check
valves in other store
equipment
Install a new water
filter
Clean/replace dump
valve as needed
See Installation
Instructions
Repair/replace as
needed
Clean/replace as
needed
Stop the water spray
Clean the ice
machine
Correct the water
flow
Remount/replace as
needed
Clean/replace water
level probe as
needed
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Refrigeration System
ICE FORMATION PATTERN 2. Extremely Thin at Evaporator Outlet
Evaporator ice formation pattern analysis is helpful
in ice machine diagnostics.
Analyzing the ice formation pattern alone cannot
diagnose an ice machine malfunction. However,
when this analysis is used along with Manitowoc’s
Refrigeration System Operational Analysis Table, it
can help diagnose an ice machine malfunction.
Improper ice formation can be caused by any
There is no ice, or a considerable lack of ice
formation on the top of the evaporator (tubing
outlet).
Examples: No ice at all on the top of the evaporator,
but ice forms on the bottom half of the evaporator.
Or, the ice at the top of the evaporator reaches 1/8”
to initiate a harvest, but the bottom of the
evaporator already has 1/2” to 1” of ice formation.
number of problems.
Example: An ice formation that is “extremely thin
ICE
on top” could be caused by a hot water supply, a
dump valve leaking water, a faulty water fill valve,
OUTLET
a low refrigerant charge, etc.
Important
Keep the water curtain in place while checking
ICE
the ice formation pattern to ensure no water is
lost.
1. Normal Ice Formation
Ice forms across the entire evaporator surface.
At the beginning of the freeze cycle, it may appear
INLET
that more ice is forming on the bottom of the
evaporator than on the top. At the end of the freeze
cycle, ice formation on the top will be close to, or
Extremely Thin Ice Formation
at Evaporator Outlet
just a bit thinner than, ice formation on the bottom.
The dimples in the cubes at the top of the
evaporator may be more pronounced than those on
the bottom. This is normal.
SV1576
The ice thickness probe must be set to maintain the
ice bridge thickness at approximately 1/8”. If ice
forms uniformly across the evaporator surface, but
does not reach 1/8” in the proper amount of time,
this is still considered normal.
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Refrigeration System
3. Extremely Thin at Evaporator Inlet 5. No Ice Formation
There is no ice, or a considerable lack of ice
formation on the bottom of the evaporator (tubing
inlet). Examples: The ice at the top of the
evaporator reaches 1/8” to initiate a harvest, but
The ice machine operates for an extended period,
but there is no ice formation at all on the
evaporator.
there is no ice formation at all on the bottom of the
evaporator.
OUTLET
ICE
INLET
SV1575
Extremely Thin Ice Formation at Evaporator
Inlet
4. Spotty Ice Formation
There are small sections on the evaporator where
there is no ice formation. This could be a single
corner, or a single spot in the middle of the
evaporator. This is generally caused by loss of heat
transfer from the tubing on the back side of the
evaporator.
OUTLET
ICE
INLET
Spotty Ice Formation
SV1577
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Refrigeration System
SAFETY LIMITS
General
In addition to standard safety controls, such as high
pressure cut-out, the control board has two built in
safety limit controls which protect the ice machine
from major component failures.
Safety Limit #1: If the freeze time reaches 60
minutes, the control board automatically initiates a
harvest cycle. If three consecutive 60-minute freeze
cycles occur, the ice machine stops.
Safety Limit #2: If the harvest time reaches 3.5
minutes, the control board automatically returns the
ice machine to the freeze cycle. If three consecutive
3.5 minute harvest cycles occur, the ice machine
stops.
Determining Which Safety Limit Stopped The Ice Machine
When a safety limit condition causes the ice
machine to stop, the harvest light on the control
board continually flashes on and off. Use the
following procedures to determine which safety
limit has stopped the ice machine.
1. Move the toggle switch to OFF.
2. Move the toggle switch back to ICE.
3. Watch the harvest light. It will flash one or two
times, corresponding to safety limits 1 and 2, to
indicate which safety limit stopped the ice
machine.
After safety limit indication, the ice machine will
restart and run until a safety limit is exceeded again.
Analyzing Why Safety Limits
May Stop the Ice Machine
According to the refrigeration industry, a high
percentage of compressors fail as a result of
external causes. These can include: flooding or
starving expansion valves, dirty condensers, water
loss to the ice machine, etc. The safety limits
protect the ice machine (primarily the compressor)
from external failures by stopping ice machine
operation before major component damage occurs.
The safety limit system is similar to a high pressure
cut-out control. It stops the ice machine, but does
not tell what is wrong. The service technician must
analyze the system to determine what caused the
high pressure cut-out, or a particular safety limit, to
stop the ice machine.
The safety limits are designed to stop the ice
machine prior to major component failures, most
often a minor problem or something external to the
ice machine. This may be difficult to diagnose, as
many external problems occur intermittently.
Example: An ice machine stops intermittently on
safety limit #1 (long freeze times). The problem
could be a low ambient temperature at night, a
water pressure drop, the water is turned off one
night a week, etc.
When a high pressure cut-out or a safety limit stops
the ice machine, they are doing what they are
supposed to do. That is, stopping the ice machine
before a major component failure occurs.
Refrigeration and electrical component failures may
also trip a safety limit. Eliminate all electrical
components and external causes first. If it appears
that the refrigeration system is causing the problem,
use Manitowoc’s Refrigeration System Operational
Analysis Table, along with detailed charts,
checklists, and other references to determine the
cause.
32
The following checklists are designed to assist the
service technician in analysis. However, because
there are many possible external problems, do not
limit your diagnosis to only the items listed.
Page 37
Refrigeration System
Safety Limit #1
Freeze time exceeds 60 minutes for 3 consecutive freeze cycles.
Possible Cause Check/Correct
Improper installation • See “Installation/Visual Inspection Checklist”
Water system • Low water pressure (20 psi min.)
• High water pressure (80 psi max.)
• High water temperature (90°F/32.2°C max.)
• C logged water distribution tube
• Dirty/defective water inlet valve
• Dirty/defective water dump valve
• Defective water pump
Electrical system • Ice thickness probe out of adjustment
• Harvest cycle not initiated electrically
• Contactor not energizing
• Compressor electrically non-operational
Restricted condenser water
flow (water-cooled models)
Refrigeration system • Non-Manitowoc components
• Low water pressure (20 psi min.)
• High water temperature (90°F/32.2°C max.)
• Dirty condenser
• Dirty/defective water regulating valve
• Water regulating valve out of adjustment
• Improper refrigerant charge
• Defective hot gas valve
• Defective compressor
• TXV starving or flooding (check bulb mounting)
• Non-cond ensibles in refrigeration system
• Plugged or restricted high side refrigerant lines or component
SAFETY LIMIT NOTES
• Because there are many possible external problems, do not limit your diagnosis to only the items listed in
this chart.
• A continuous run of 100 harvests automatically erases the safety limit code.
• The control board will store and indicate only one safety limit – the last one exceeded.
• If the toggle switch is moved to the OFF position and then back to the ICE position prior to reaching the
100-harvest point, the last safety limit exceeded will be indicated.
• If the harvest light did not flash prior to the ice machine restarting, then the ice machine did not stop
because it exceeded a safety limit.
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Refrigeration System
Safety Limit #2
Harvest time exceeds 3.5 minutes for 3 consecutive harvest cycles.
Possible Cause Check/Correct
Improper installation • See “Installation/Visual Inspection Checklist”
Water system • Water area (evaporator) dirty
• Dirty/defective water dump valve
• Vent tube not installed on water outlet drain
• Water freezing behind evaporator
• P lastic extrusions and gaskets not securely mounted to the evaporator
• Low water pressure (20 psi min.)
• Loss of water from sump area
• C logged water distribution tube
• Dirty/defective water inlet valve
• Defective water pump
Electrical system • Ice thickness probe out of adjustment
• Ice thickness probe dirty
• Bin switch defective
• Premature harvest
Refrigeration system • Non-Manitowoc components
• Water regulating valve dirty/defective
• Improper refrigerant charge
• Defective hot gas valve
• TXV flooding (check bulb mounting)
SAFETY LIMIT NOTES
• Because there are many possible external problems, do not limit your diagnosis to only the items listed in
this chart.
• A continuous run of 100 harvests automatically erases the safety limit code.
• The control board will store and indicate only one safety limit – the last one exceeded.
• If the toggle switch is moved to the OFF position and then back to the ICE position prior to reaching the
100-harvest point, the last safety limit exceeded will be indicated.
• If the harvest light did not flash prior to the ice machine restarting, then the ice machine did not stop
because it exceeded a safety limit.
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Refrigeration System
SINGLE EXPANSION VALVE ICE MACHINES COMPARING EVAPORATOR INLET AND OUTLET TEMPERATURES
The temperatures of the suction lines entering and
leaving the evaporator alone cannot diagnose an
ice machine. However, comparing these
temperatures during the freeze cycle, along with
using Manitowoc’s Refrigeration System
Operational Analysis Table, can help diagnose an
ice machine malfunction.
The actual temperatures entering and leaving the
evaporator vary by model, and change throughout
the freeze cycle. This makes documenting the
“normal” inlet and outlet temperature readings
difficult. The key to the diagnosis lies in the
difference between the two temperatures five
minutes into the freeze cycle. These temperatures
must be within 7° of each other.
Use this procedure to document freeze cycle inlet
and outlet temperatures.
1. Use a quality temperature meter, capable of
taking temperature readings on curved copper
lines.
2. Attach the temperature meter sensing device to
the copper lines entering and leaving the
evaporator.
Important
Do not simply insert the sensing device under the
insulation. It must be attached to and reading the
actual temperature of the copper line.
3. Wait five minutes into the freeze cycle.
4. Record the temperatures below and determine
the difference between them.
5. Use this with other information gathered on
the Refrigeration System Operational Analysis
Table to determine the ice machine
malfunction.
______________ _____________
Inlet Temperature
______________
Must be within 7°F at 5
minutes into freeze cycle
Difference
Outlet Temperature
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Refrigeration System
HOT GAS VALVE TEMPERATURE CHECK
General
A hot gas valve requires a critical orifice size. This
meters the amount of hot gas flowing into the
evaporator during the harvest cycle. If the orifice is
even slightly too large or too small, long harvest
cycles will result.
A too-large orifice causes refrigerant to condense to
liquid in the evaporator during the harvest cycle.
This liquid will cause compressor damage. A toosmall orifice does not allow enough hot gas into the
evaporator. This causes low suction pressure, and
insufficient heat for a harvest cycle.
Normally, a defective hot gas valve can be rebuilt.
Refer to the Parts Manual for proper valve
application and rebuild kits. If replacement is
necessary, Use only “original” Manitowoc
replacement parts.
Hot Gas Valve Analysis
Symptoms of a hot gas valve remaining partially
open during the freeze cycle can be similar to
symptoms of either an expansion valve or
compressor problem. The best way to diagnose a
hot gas valve is by using Manitowoc’s Ice Machine
Refrigeration System Operational Analysis Table.
Use the following procedure and table to help
determine if a hot gas valve is remaining partially
open during the freeze cycle.
1. Wait five minutes into the freeze cycle.
2. Feel the inlet of the hot gas valve(s).
Important
Feeling the hot gas valve outlet or across the hot
gas valve itself will not work for this comparison.
3. Feel the compressor discharge line.
WARNING
The inlet of the hot gas valve and the compressor
discharge line could be hot enough to burn your
hand. Just touch them momentarily.
4. Compare the temperature of the inlet of the hot
gas valves to the temperature of the compressor
discharge line.
Findings Comments
The inlet of the
hot gas valve is
cool enough to
touch and the
compressor
discharge line is
hot.
The inlet of the
hot gas valve is
hot and
approaches the
temperature of
a hot
compressor
discharge line.
Both the inlet of
the hot gas
valve and the
compressor
discharge line
are cool enough
to touch.
This is normal as the discharge
line should always be too hot to
touch and the hot gas valve
inlet, although too hot to touch
during harvest, should be cool
enough to touch after 5
minutes into the freeze cycle.
This is an indication something is
wrong, as the hot gas valve
inlet did not cool down during
the freeze cycle. If the
compressor dome is also
entirely hot, the problem is not
a hot gas valve leaking, but
rather som ething causing the
compressor (and the entire ice
machine) to get hot.
This is an indication something is
wrong, causing the compressor
discharge line to be cool to the
touch. This is not caused by a
hot gas valve leaking.
The hot gas valve outlet is on the suction side
(cool refrigerant). It may be cool enough to touch
even if the valve is leaking.
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Refrigeration System
ANALYZING DISCHARGE PRESSURE DURING FREEZE OR HARVEST CYCLE
1. Determine the ice machine operating conditions:
Air temp. entering condenser ______
Air temp. around ice machine ______
Water temp. entering sump trough ______
2. Refer to Operating Pressure Chart for ice
machine being checked.
Use the operating conditions determined in Step
1 to find the published normal discharge
pressures.
Freeze Cycle ______ Harvest Cycle ______
3. Perform an actual discharge pressure check.
Freeze
Cycle PSIG
Beginning of Cycle __________ __________
Middle of Cycle __________ __________
End of Cycle __________ __________
4. Compare the actual discharge pressure (Step 3)
with the published discharge pressure (Step 2).
The discharge pressure is normal when the
actual pressure falls within the published
pressure range for the ice machine’s operating
conditions.
Freeze Cycle Discharge Pressure High Checklist
Possible Cause Check/Correct
Improper installation • See “Installation/Visual Inspection Checklist”
Restricted condenser water
flow (water-cooled models)
Improper refrigerant charge • Overcharged
Other • Non-Manitowoc components in system
• Low water pressure (20 psi min.)
• High inlet water temperature (90°F/32.2°C max.)
• Dirty condenser
• Dirty/defective water regulating valve
• Water regulating valve out of adjustment
• Non-condensibles in system
• Wrong type of refrigerant
• High side refrigerant lines/component restricted (before mid-
condenser)
Freeze Cycle Discharge Pressure Low Checklist
Possible Cause Check/Correct
Improper installation • See “Installation/Visual Inspection Checklist”
Improper refrigerant charge • Undercharged
• Wrong type of refrigerant
Water regulating valve
(water-cooled condensers)
Other • Non-Manitowoc components in system
• Out of adjustment
• Defective
NOTE: Do not limit your diagnosis to only the items listed in the checklists.
Harvest
Cycle PSIG
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Refrigeration System
ANALYZING SUCTION PRESSURE DURING FREEZE CYCLE
The suction pressure gradually drops throughout
the freeze cycle. The actual suction pressure (and
drop rate) changes as the air and water
temperatures entering the ice machine change.
This affects freeze cycle times.
To analyze and identify the proper suction
pressure drop throughout the freeze cycle,
compare the published suction pressure to the
published freeze cycle time. “Operating Pressure”
and “Freeze Cycle Time” charts can be found later
in this section.
NOTE: Analyze discharge pressure before
analyzing suction pressure. High or low discharge
pressure may be causing high or low suction
pressure.
Procedure
Step Example Using QD800W Model Ice Machine
1. Determine the ice machine operating
conditions.
2A. Refer to “Cycle Time” and “Operating
Pressure” charts for ice machine model
being checked. Using operating conditions
from Step 1, determine published freeze
cycle time and published freeze cycle
suction pressure.
Published Freeze Cycle Time (minutes)
2B. Compare the published freeze cycle time
and published freeze cycle suction
pressure. Develop a chart.
Published Freeze Cycle Suction Pressure (psig)
3. Perform an actual suction pressure check
at the beginning, middle and end of the
freeze cycle. Note the times at which the
readings are taken.
4. Compare the actual freeze cycle suction
pressure (Step 3) to the published freeze
cycle time and pressure comparison (Step
2B). Determine if the suction pressure is
high, low or acceptable.
Air temp. around ice machine: 80°F/26.7°C
Water temp. entering water fill valve:
Published freeze cycle
time:
9.7-11.1
1 3 5 7 10
34 30 27 24 20
Beginning of freeze cycle:
Middle of freeze cycle:
End of freeze cycle:
Time Into
Freeze Cycle
1 minutes
5 minutes
10 minutes
minutes PSIG
Published
Pressure
40 PSIG
29 PSIG
18 PSIG
Published freeze cycle
suction pressure:
59 PSIG at 1 minute
48 PSIG at 5 minutes
40 PSIG at 10 minutes
Actual
Pressure
59 PSIG
48 PSIG
40 PSIG
34-20
70°F/21.1°C
Result
High
High
High
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Refrigeration System
Freeze Cycle Suction Pressure High Checklist
Possible Cause Check/Correct
Improper installation • See “Installation/Visual Inspection Checklist”
Discharge pressure • Discharge pressure is too high, and is affecting low side (See “Freeze
Cycle Discharge Pressure High Checklist”)
Improper refrigerant charge • Overcharged
• Wrong type of refrigerant
Other • Non-Manitowoc components in system
• Hot gas valve stuck open
• TXV flooding (check bulb mounting)
• Defective compressor
Freeze Cycle Suction Pressure Low Checklist
Possible Cause Check/Correct
Improper installation • See “Installation/Visual Inspection Checklist”
Discharge pressure • Discharge pressure is too low, and is affecting low side (See “Freeze
Cycle Discharge Pressure Low Checklist”)
Improper refrigerant charge • Undercharged
• Wrong type of refrigerant
Other • Non-Manitowoc components in system
• Improper water supply over evaporator (See “Water System Checklist”)
• Loss of heat transfer from tubing on back side of evaporator
• Restricted/plugged liquid line drier
• Restricted/plugged tubing in suction side of refrigeration system
• TXV starving
NOTE: Do not limit your diagnosis to only the items listed in the checklists.
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Refrigeration System
HOW TO USE THE REFRIGERATION SYSTEM OPERATIONAL ANALYSIS TABLES
General
These tables must be used with charts, checklists
and other references to eliminate refrigeration
components not listed on the tables and external
items and problems which can cause good
refrigeration components to appear defective.
The tables list five different defects that may affect
the ice machine’s operation.
NOTE: A low-on-charge ice machine and a starving
expansion valve have very similar characteristics
and are listed under the same column.
NOTE: Before starting, see “Before Beginning
Service for a few questions to ask when talking to
the ice machine owner.
Procedure
Step 1 Complete the “Operation Analysis” column.
Read down the left “Operational Analysis” column.
Perform all procedures and check all information
listed. Each item in this column has supporting
reference material to help analyze each step.
While analyzing each item separately, you may find
an “external problem” causing a good refrigerant
component to appear bad. Correct problems as they
are found. If the operational problem is found, it is
not necessary to complete the remaining
procedures.
Step 2 Enter check marks in the small boxes.
Each time the actual findings of an item in the
“Operational Analysis” column matches the
published findings on the table, enter a check mark.
Example: Freeze cycle suction pressure is
determined to be low. Enter a check mark in the
“low” box.
Step 3 Add the check marks listed under each of
the four columns. Note the column number with the
highest total and proceed to “Final Analysis.”
NOTE: If two columns have matching high
numbers, a procedure was not performed properly
and/or supporting material was not analyzed
correctly.
Final Analysis
The column with the highest number of check
marks identifies the refrigeration problem.
COLUMN 1 - HOT GAS VALVE LEAKING
Normally, a leaking hot gas valve can be repaired
with a rebuild kit instead of changing the entire
valve. Rebuild or replace the valve as required.
COLUMN 2 - LOW CHARGE/TXV STARVING
Normally, a starving expansion valve only affects
the freeze cycle pressures, not the harvest cycle
pressures. A low refrigerant charge normally affects
both pressures. Verify the ice machine is not low on
charge before replacing an expansion valve.
1. Add refrigerant charge in 2 to 4 oz. increments
as a diagnostic procedure to verify a low charge.
If the problem is corrected, the ice machine is
low on charge. Find the refrigerant leak.
The ice machine must operate with the
nameplate charge. If the leak cannot be found,
proper refrigerant procedures must still be
followed Change the liquid line drier. Then,
evacuate and weigh in the proper charge.
2. If the problem is not corrected by adding
charge, the expansion valve is faulty.
On dual expansion valve ice machines, change
only the TXV that is starving. If both TXV’s are
starving, they are probably good, and are being
affected by some other malfunction, such as low
charge.
COLUMN 3 - TXV FLOODING
A loose or improperly mounted expansion valve
bulb causes the expansion valve to flood. Check
bulb mounting, insulation, etc., before changing the
valve. On dual expansion valve machines, the
service technician should be able to tell which TXV
is flooding by analyzing ice formation patterns.
Change only the flooding expansion valve.
COLUMN 4 - COMPRESSOR
Replace the compressor and start components. To
receive warranty credit, the compressor ports must
be properly sealed by crimping and soldering them
closed. Old start components must be returned with
the faulty compressor.
40
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Refrigeration System
Q Model Single Expansion Valve
Refrigeration System Operational Analysis Table
This table must be used with charts, checklists and other references to eliminate refrigeration components not listed on the table
and external items and problems which can cause good refrigeration components to appear defective.
Operational Analysis 1 2 3 4
(listed below)
Ice Production
Safety limits
Refer to "Analyzing Safety
Limits" to eliminate problems
and/or components not listed
on this table
Ice Formation Pattern
_______________________
_______________________
_______________________
_______________________
Wait 5 minutes into the
freeze cycle.
Compare temperatures
of evaporator inlet and
evaporator outlet.
Inlet ______ °F
Outlet ______ °F
Difference ______ °F
Wait 5 minutes into the
freeze cycle.
Compare temperatures
of compressor
discharge line and hot
gas valve inlet.
Comp. Disc. ______ °F
Hot Gas Inlet ______ °F
Freeze cycle
DISCHARGE pressure
_______ _______ _______
1 minute Middle End
into cycle
Freeze cycle
SUCTION pressure
________ _______ _______ Suction pressure is Suction pressure is Suction pressure is Suction pressure is
Beginning Middle End
Miscellaneous
Enter items in proper boxes.
Final Analysis
Enter total number of
boxes checked in each
column.
Published 24 hour ice production _____________
Calculated (actual) ice production _____________
NOTE: The ice machine is operating properly if the ice producti on
and ice formation pattern is normal
Stops on safety limit:
extremely thin on top
No ice formation on
entire evaporator
The hot gas valve inlet
approaches the
temperature of a Hot
compressor discharge
If discharge pressure is High or Low refer to a freeze cycle high or low discharge pressure problem
checklist to eliminate problems and/or components not listed on this table before proceeding.
If suction pressure is High or Low refer to a freeze cycle high or low suction pressure problem checklist
to eliminate problems and/or components not listed on this table before proceeding.
Hot gas valve leaking Low on charge TXV Flooding Compressor
1
Ice formation is
of evaporator
-or-
Inlet and ou tlet
within 7°F
of each other
is Hot
-and-
line.
High Low High High
Stops on safety limit:
Ice formation is
extremely thin on top
of evaporator
No ice formation on
entire evaporator
Inlet is colder than
The hot gas valve inlet
to hold hand on
the compressor
discharge line is Hot.
1
-or-
Inlet and outlet
within 7°F
not
of each other
-andoutlet
is cool enough
-and-
-or-
TXV Starving
Stops on safety limit:
Ice formation normal
extremely thin on
bottom of evaporator
No ice formation on
entire evaporator
Inlet is warmer than
The hot gas valve inlet
to hold hand on
discharge line is cool
to hold hand on.
1 or 2
-or-
Ice formation is
-or-
Inlet and ou tlet
within 7°F
of each other
-or-
Inlet and ou tlet
within 7°F
not
of each other
-andoutlet
is cool enough
-and-
the compressor
enough
Stops on safety limit:
1
Ice formation normal
-or-
No ice formation on
entire evaporator
Inlet and ou tlet
within 7°F
of each other
The hot gas valve inlet
is cool enough
to hold hand on
-and-
the compressor
discharge line is Hot.
MANITOWOC ICE, INC.
2110 South 26th Street P.O. Box 1720 Manitowoc, WI 54221-1720
Phone: (920) 682-0161 Service Fax: (920) 683-7585 Web Site - www.manitowocice.com
41
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Refrigeration System
Pressure Control Specifications and Diagnostics
HIGH PRESSURE CUTOUT
(HPCO) CONTROL
Function
Stops the ice machine if subjected to excessive
high-side pressure.
The HPCO control is normally closed, and opens on
a rise in discharge pressure.
Specifications
Cut-out: 450 psig ±10
Cut-in: Manual or automatic reset
(Must be below 300 psig to reset).
Check Procedure
1. Set ICE/OFF/CLEAN switch to OFF, (Manual
reset HPCO reset if tripped).
2. Connect manifold gauges.
3. Hook voltmeter in parallel across the HPCO,
leaving wires attached.
4. On water-cooled models, close the water service
valve to the water condenser inlet. On selfcontained air-cooled and remote models,
disconnect the fan motor.
5. Set ICE/OFF/CLEAN switch to ICE.
6. No water or air flowing through the condenser
will cause the HPCO control to open because of
excessive pressure. Watch the pressure gauge
and record the cut-out pressure.
WARNING
If discharge pressure exceeds 460 psig and the
HPCO control does not cut out, set
ICE/OFF/CLEAN switch to OFF to stop ice
machine operation.
Replace the HPCO control if it:
• Will not reset (below 300 psig)
• Does not open at the specified cut-out point
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Refrigeration System
Cycle Time/24 Hour Ice Production/Refrigerant Pressure Charts
Q800 SERIES WATER-COOLED
NOTE: These characteristics may vary depending
on operating conditions.
Cycle Times
Freeze Time + Harvest Time = Cycle Time
Air Temp. Freeze Time Harvest
Around Ice
Machine
°F/°C
70/21.1
80/26.7
90/32.2
100/37.8
1
Times in minutes
Water Temperature °F/°C
50/10.0 70/21.1 90/32.2
8.7-10.1 9.5-11.0 10.9-12.5
8.9-10.2 9.7-11.1 11.0-12.7
9.0-10.3 9.8-11.3 11.2-12.9
9.1-10.5 10.0-11.5 11.4-13.1
Time
1-2.5
24 Hour Ice Production
Air Temp.
Around Ice
Machine
°F/°C
70/21.1
80/26.7
90/32.2
100/37.8
1
Based on average ice slab weight of 5.75 - 6.50 lb.
2
Regular cube derate is 7%
50/10.0
Water Temperature °F/°C
810 750 670
800 740 660
790 730 650
780 720 640
70/21.1
90/32.2
Condenser 90/32.2 Air Temperature Around Ice Machine
Water
Consumption
Gal/24 hours
1
Water regulating valve set to maintain 230 PSIG discharge
pressure
50/10.0 70/21.1 90/32.2
Water Temperature °F/°C
640 1420 6000
Operating Pressures
Air Temp. Freeze Cycle Harvest Cycle
Around Ice
Machine
°F/°C
50/10.0
70/21.1
80/26.7
90/32.2
100/37.8
110/43.3
1
Suction pressure drops gradually throughout the freeze cycle
Discharge
Pressure
PSIG
225-235 33-20 160-185 65-85
225-235 34-20 165-185 70-85
225-235 34-20 165-185 70-85
225-235 36-22 165-185 70-85
225-235 36-22 165-185 70-85
225-240 38-24 170-190 75-90
Suction
Pressure
PSIG
Discharge
Pressure
PSIG
Suction
Pressure
PSIG
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Refrigeration System
Refrigerant Recovery/Evacuation and Recharging
NORMAL SELF-CONTAINED MODEL
PROCEDURES
Refrigerant Recovery/Evacuation
Do not purge refrigerant to the atmosphere. Capture
refrigerant using recovery equipment. Follow the
manufacturer’s recommendations.
Important
Manitowoc Ice, Inc. assumes no responsibility for
the use of contaminated refrigerant. Damage
resulting from the use of contaminated refrigerant
is the sole responsibility of the servicing
company.
Important
Replace the liquid line drier before evacuating
and recharging. Use only a Manitowoc (O.E.M.)
liquid line filter drier to prevent voiding the
warranty.
CONNECTIONS
1. Suction side of the compressor through the
suction service valve.
2. Discharge side of the compressor through the
discharge service valve.
SELF-CONTAINED RECOVERY/EVACUATION
1. Place the toggle switch in the OFF position.
2. Install manifold gauges, charging cylinder/scale,
and recovery unit or two-stage vacuum pump.
LOW SIDE
SERVICE
VALVE
CHARGING
CYLINDER
CLOSED
Recovery/Evacuation Connections
3. Open (backseat) the high and low side ice
machine service valves, and open high and low
side on manifold gauges.
4. Perform recovery or evacuation:
A. Recovery: Operate the recovery unit as
directed by the manufacturer’s instructions.
B. Evacuation prior to recharging: Pull the
system down to 250 microns. Then, allow
the pump to run for an additional half hour.
Turn off the pump and perform a standing
vacuum leak check.
NOTE: Check for leaks using a halide or electronic
leak detector after charging the ice machine.
5. Follow the Charging Procedures on the next
page.
MANIFOLD SET
OPEN
OPEN
BACKSEATED BACKSEATED
HIGH SIDE
SERVICE
VALVE
OPEN
VACUUM PUMP/
RECOVERY UNIT
SV1404A
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Self-Contained Charging Procedures
Refrigeration System
Important
The charge is critical on all Manitowoc ice
machines. Use a scale or a charging cylinder to
ensure the proper charge is installed.
1. Be sure the toggle switch is in the OFF
position.
CLOSED
MANIFOLD SET
BACKSEATED FRONTSEATED
OPEN
HIGH SIDE
SERVICE
VALVE
VACUUM PUMP/
RECOVERY UNIT
CLOSED
SV1404B
LOW SIDE
SERVICE
VALVE
CHARGING
CYLINDER
OPEN
Charging Connections
2. Close the vacuum pump valve, the low side
service valve, and the low side manifold gauge
valve.
3. Open the high side manifold gauge valve, and
backseat the high side service valve.
4. Open the charging cylinder and add the proper
refrigerant charge (shown on nameplate)
through the discharge service valve.
5. Let the system “settle” for 2 to 3 minutes.
6. Place the toggle switch in the ICE position.
7. Close the high side on the manifold gauge set.
Add any remaining vapor charge through the
suction service valve (if necessary).
NOTE: Manifold gauges must be removed
properly to ensure that no refrigerant
contamination or loss occurs.
8. Make sure that all of the vapor in the charging
hoses is drawn into the ice machine before
disconnecting the charging hoses.
A. Run the ice machine in freeze cycle.
B. Close the high side service valve at the ice
machine.
C. Open the low side service valve at the ice
machine.
D. Open the high and low side valves on the
manifold gauge set. Any refrigerant in the
lines will be pulled into the low side of the
system.
E. Allow the pressures to equalize while the
ice machine is in the freeze cycle.
F. Close the low side service valve at the ice
machine.
Remove the hoses from the ice machine and install
the caps.
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Refrigeration System
SYSTEM CONTAMINATION CLEANUP
General
This section describes the basic requirements for
restoring contaminated systems to reliable service.
Important
Manitowoc Ice, Inc. assumes no responsibility for
the use of contaminated refrigerant. Damage
resulting from the use of contaminated refrigerant
is the sole responsibility of the servicing
company.
Determining Severity Of Contamination
System contamination is generally caused by
either moisture or residue from compressor
burnout entering the refrigeration system.
Inspection of the refrigerant usually provides the
first indication of system contamination. Obvious
moisture or an acrid odor in the refrigerant
indicates contamination.
If either condition is found, or if contamination is
suspected, use a Total Test Kit from Totaline or a
similar diagnostic tool. These devices sample
refrigerant, eliminating the need to take an oil
sample. Follow the manufacturer’s directions.
If a refrigerant test kit indicates harmful levels of
contamination, or if a test kit is not available,
inspect the compressor oil.
1. Remove the refrigerant charge from the ice
machine.
2. Remove the compressor from the system.
3. Check the odor and appearance of the oil.
4. Inspect open suction and discharge lines at the
compressor for burnout deposits.
5. If no signs of contamination are present,
perform an acid oil test.
Check the chart below to determine the type of
cleanup required.
Contamination/Cleanup Chart
Symptoms/Findings Required Cleanup Procedure
No symptoms or suspicion of contamination Normal evacuation/recharging procedure
Moisture/Air Contamination symptoms
• Refrigeration system open to atmosphere for
longer than 15 minutes
• Refrigeration test kit and/or acid oil test shows
contamination
• Leak in water-cooled condenser
• No burnout deposits in open compressor lines
Mild Compressor Burnout symptoms
• Oil appears clean but smells acrid
• Refrigeration test kit or acid oil test shows harmful
acid content
• No burnout deposits in open compressor lines
Severe Compressor Burnout symptoms
• Oil is discolored, acidic, and smells acrid
• Burnout deposits found in the compressor and
lines, and in other components
Mild contamination cleanup procedure
Mild contamination cleanup procedure
Severe contamination cleanup procedure
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Mild System Contamination Cleanup
Procedure
1. Replace any failed components.
2. If the compressor is good, change the oil.
3. Replace the liquid line drier.
NOTE: If the contamination is from moisture, use
heat lamps during evacuation. Position them at the
compressor, condenser and evaporator prior to
evacuation. Do not position heat lamps too close
to plastic components, or they may melt or warp.
Important
Dry nitrogen is recommended for this procedure.
This will prevent CFC release.
4. Follow the normal evacuation procedure,
except replace the evacuation step with the
following:
A. Pull vacuum to 1000 microns. Break the
vacuum with dry nitrogen and sweep the
system. Pressurize to a minimum of 5 psi.
B. Pull vacuum to 500 microns. Break the
vacuum with dry nitrogen and sweep the
system. Pressurize to a minimum of 5 psi.
C. Change the vacuum pump oil.
D. Pull vacuum to 250 microns. Run the
vacuum pump for 1/2 hour on selfcontained models, 1 hour on remotes.
NOTE: You may perform a standing vacuum test
to make a preliminary leak check. You should use
an electronic leak detector after system charging
to be sure there is no leak.
5. Charge the system with the proper refrigerant
to the nameplate charge.
6. Operate the ice machine.
Refrigeration System
Severe System Contamination Cleanup
Procedure
1. Remove the refrigerant charge.
2. Remove the compressor.
3. Disassemble the hot gas solenoid valve. If
burnout deposits are found inside the valve,
install a rebuild kit, and replace manifold
strainer, TXV valve.
4. Wipe away any burnout deposits from suction
and discharge lines at compressor.
5. Sweep through the open system with dry
nitrogen.
Important
Refrigerant sweeps are not recommended, as they
release CFC’s into the atmosphere.
7. Install a new compressor and new start
components.
8. Install a suction line filter-drier with acid and
moisture removal capability (P/N 89-3028-3).
Place the filter drier as close to the compressor
as possible.
9. Install an access valve at the inlet of the
suction line drier.
10. Install a new liquid line drier.
Continued on next page
47
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Refrigeration System
11. Follow the normal evacuation procedure, except
replace the evacuation step with the following:
Important
Dry nitrogen is recommended for this procedure.
This will prevent CFC release.
A. Pull vacuum to 1000 microns. Break the
vacuum with dry nitrogen and sweep the
system. Pressurize to a minimum of 5 psi.
B. Change the vacuum pump oil.
C. Pull vacuum to 500 microns. Break the
vacuum with dry nitrogen and sweep the
system. Pressurize to a minimum of 5 psi.
D. Change the vacuum pump oil.
E. Pull vacuum to 250 microns. Run the
vacuum pump for 1/2 hour on self-contained
models, 1 hour on remotes.
NOTE: You may perform a standing vacuum test to
make a preliminary leak check. You should use an
electronic leak detector after system charging to be
sure there is no leak.
12. Charge the system with the proper refrigerant to
the nameplate charge.
13. Operate the ice machine for one hour. Then,
check the pressure drop across the suction line
filter-drier.
A. If the pressure drop is less than 1 psi, the
filter-drier should be adequate for complete
cleanup.
B. If the pressure drop exceeds 1 psi, change
the suction line filter-drier and the liquid
line drier. Repeat until the pressure drop is
acceptable.
14. Operate the ice machine for 48-72 hours. Then,
remove the suction line drier and change the
liquid line drier.
15. Follow normal evacuation procedures.
REPLACING PRESSURE CONTROLS
WITHOUT REMOVING REFRIGERANT
CHARGE
This procedure reduces repair time and cost. Use it
when any of the following components require
replacement, and the refrigeration system is
operational and leak-free.
• Water regulating valve (water-cooled only)
• High pressure cut-out control
• High side service valve
• Low side service valve
Important
This is a required in-warranty repair procedure.
1. Disconnect power to the ice machine.
2. Follow all manufacturer’s instructions supplied
with the pinch-off tool. Position the pinch-off
tool around the tubing as far from the pressure
control as feasible. (See the figure on next
page.) Clamp down on the tubing until the
pinch-off is complete.
WARNING
Do not unsolder a defective component. Cut it out
of the system. Do not remove the pinch-off tool
until the new component is securely in place.
3. Cut the tubing of the defective component with
a small tubing cutter.
4. Solder the replacement component in place.
Allow the solder joint to cool.
5. Remove the pinch-off tool.
6. Re-round the tubing. Position the flattened
tubing in the proper hole in the pinch off tool.
Tighten the wingnuts until the block is tight and
the tubing is rounded. (See the drawing on next
page.)
NOTE: The pressure controls will operate normally
once the tubing is re-rounded. Tubing may not reround 100%..
48
Page 53
Refrigeration System
FIG. A - “PINCHING OFF” TUBING
TYPICAL PRESSURE
CONTROL SHOWN
“PINCH-OFF” TOOL USED HERE
SEE FIG. A AND FIG. B
FIG. B - RE-ROUNDING TUBING
SV1406
Using Pinch-Off Tool
49
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Refrigeration System
FILTER-DRIERS
The filter-driers used on Manitowoc ice machines
are manufactured to Manitowoc specifications.
The difference between Manitowoc driers and offthe-shelf driers is in filtration. Manitowoc driers
have dirt-retaining filtration, with fiberglass filters
on both the inlet and outlet ends. This is very
important because ice machines have a backflushing action which takes place during every
harvest cycle.
These filter-driers have a very high moisture
removal capability and a good acid removal
capacity.
The size of the filter-drier is important. The
refrigerant charge is critical. Using an improperly
sized filter-drier will cause the ice machine to be
improperly charged with refrigerant.
TOTAL SYSTEM REFRIGERANT CHARGES
Important
Refer to the ice machine serial number tag to
verify the system charge.
Series Version Charge
Q 1000 Water Cooled 32 oz.
NOTE: Charged using R-404A refrigerant.
Listed below are the recommended O.E.M. field
replacement driers:
Important
Driers are covered as a warranty part. The drier
must be replaced any time the system is opened
for repairs.
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REFRIGERANT DEFINITIONS
Recover
To remove refrigerant, in any condition, from a
system and store it in an external container, without
necessarily testing or processing it in any way.
Recycle
To clean refrigerant for re-use by oil separation and
single or multiple passes through devices, such as
replaceable core filter-driers, which reduce
moisture, acidity and particulate matter. This term
usually applies to procedures implemented at the
field job site or at a local service shop.
Refrigeration System
Reclaim
To reprocess refrigerant to new product
specifications (see below) by means which may
include distillation. A chemical analysis of the
refrigerant is required after processing to be sure
that product specifications are met. This term
usually implies the use of processes and procedures
available only at a reprocessing or manufacturing
facility.
Chemical analysis is the key requirement in this
definition. Regardless of the purity levels reached
by a reprocessing method, refrigerant is not
considered “reclaimed” unless it has been
chemically analyzed and meets ARI Standard 700
(latest edition).
New Product Specifications
This means ARI Standard 700 (latest edition).
Chemical analysis is required to assure that this
standard is met.
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Refrigeration System
REFRIGERANT RE-USE POLICY
Manitowoc recognizes and supports the need for
proper handling, re-use, and disposal of, CFC and
HCFC refrigerants. Manitowoc service procedures
require recapturing refrigerants, not venting them to
the atmosphere.
It is not necessary, in or out of warranty, to reduce
or compromise the quality and reliability of your
customers’ products to achieve this.
Important
Manitowoc Ice, Inc. assumes no responsibility for
use of contaminated refrigerant. Damage
resulting from the use of contaminated,
recovered, or recycled refrigerant is the sole
responsibility of the servicing company.
Manitowoc approves the use of:
1. New Refrigerant
• Must be of original nameplate type.
2. Reclaimed Refrigerant
• Must be of original nameplate type.
• Must meet ARI Standard 700 (latest edition)
specifications.
3. Recovered or Recycled Refrigerant
• Must be recovered or recycled in accordance
with current local, state and federal laws.
• Must be recovered from and re-used in the
same Manitowoc product. Re-use of
recovered or recycled refrigerant from other
products is not approved.
• Recycling equipment must be certified to
ARI Standard 740 (latest edition) and be
maintained to consistently meet this
standard.
• Recovered refrigerant must come from a
“contaminant-free” system. To decide
whether the system is contaminant free,
consider:
• Type(s) of previous failure(s)
• Whether the system was cleaned,
evacuated and recharged properly
following failure(s)
• Whether the system has been
contaminated by this failure
• Compressor motor burnouts and
improper past service prevent refrigerant
re-use.
• Refer to “System Contamination
Cleanup” to test for contamination.
4. “Substitute” or “Alternative” Refrigerant
• Must use only Manitowoc-approved
alternative refrigerants.
• Must follow Manitowoc-published
conversion procedures.
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HFC REFRIGERANT QUESTIONS AND ANSWERS
Manitowoc uses R-404A and R-134A HFC
refrigerants with ozone depletion potential (ODP)
factors of zero (0.0). R-404A is used in ice
machines and reach-in freezers and R-134A is used
in reach-in refrigerators.
1. What compressor oil does Manitowoc require
for use with HFC refrigerants?
Manitowoc products use Polyol Ester (POE)
type compressor oil. It is the lubricant of choice
among compressor manufacturers.
2. What are some of the characteristics of POE
oils?
They are hygroscopic, which means they have
the ability to absorb moisture. POE oils are 100
times more hygroscopic than mineral oils. Once
moisture is absorbed into the oil, it is difficult to
remove, even with heat and vacuum. POE oils
are also excellent solvents, and tend to “solvent
clean” everything inside the system, depositing
material where it is not wanted.
3. What do these POE oil characteristics mean to
me?
You must be more exacting in your procedures.
Take utmost care to prevent moisture from
entering the refrigeration system. Refrigeration
systems and compressors should not be left
open to the atmosphere for more than 15
minutes. Keep oil containers and compressors
capped at all times to minimize moisture entry.
Before removing the system charge to replace a
faulty component, be sure you have all of the
needed components at the site. Remove new
system component plugs and caps just prior to
brazing. Be prepared to connect a vacuum pump
immediately after brazing.
Refrigeration System
4. Are there any special procedures required if a
POE system is diagnosed with a refrigerant
leak?
For systems found with positive refrigerant
system pressure, no special procedures are
required.
For systems found without any positive
refrigerant pressure, assume that moisture has
entered the POE oil. After the leak is found and
repaired, the compressor oil must be changed.
The compressor must be removed and at least
95% of the oil drained from the suction port of
the compressor. Use a “measuring cup” to
replace the old oil with exactly the same amount
of new POE oil, such as Mobil EAL22A.
Remember, care must be taken to prevent
moisture from getting into the refrigeration
system during refrigeration repairs.
5. How do I leak-check a system containing HFC
refrigerant?
Use equipment designed for HFC detection. Do
not use equipment designed for CFC detection.
Consult leak detection equipment manufacturers
for their recommendations. Also, standard soap
bubbles will work with HFC refrigerants.
6. Does Manitowoc use a special liquid line filter-
drier with HFC refrigerants?
Yes. Manitowoc uses an ALCO “UK” series
filter-drier for increased filtration and moisture
removal. During a repair, Manitowoc
recommends installing the drier just before
hooking up a vacuum pump.
Continued on next page...
53
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Refrigeration System
7. Is other special equipment required to service
HFC refrigerants?
No. Standard refrigeration equipment such as
gauges, hoses, recovery systems, vacuum
pumps, etc., are generally compatible with
HFC refrigerants. Consult your equipment
manufacturer for specific recommendations for
converting existing equipment to HFC usage.
Once designated (and calibrated, if needed) for
HFC use, this equipment should be used
specifically with HFC refrigerants only.
8. Do I have to recover HFC refrigerants?
Yes. Like other refrigerants, government
regulations require recovering HFC
refrigerants.
9. Will R-404A or R-134A separate if there is a
leak in the system?
No. Like R-502, the degree of separation is too
small to detect.
10. How do I charge a system with HFC
refrigerant?
The same as R-502. Manitowoc recommends
charging only liquid refrigerant into the high side
of the system.
54
Page 59
55
Page 60
Page 61
We reserve the right to make product
improvements at any time.
Specifications and design are subject
to change without notice.
MANITOWOC ICE, INC.
2110 South 26th Street P.O. Box 1720
Manitowoc, WI 54221-1720
Web Site - www.manitowocice.com
Phone: (920) 682-0161
Fax: (920) 683-7585
©2001 Manitowoc Ice, Inc.
Litho in U.S.A.
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