Manitowoc STH042 4/16 Technician's Manual

Undercounter Ice Machines

Technician’s Handbook

This manual is updated as new information and models
are released. Visit our website for the latest manual.
www.manitowocice.com

Part Number STH042 4/16

Safety Notices

Read these precautions to prevent personal injury:

• Read this manual thoroughly before operating,
installing or performing maintenance on the
equipment. Failure to follow instructions in this
manual can cause property damage, injury or death.

• Routine adjustments and maintenance procedures
outlined in this manual are not covered by the
warranty.

• Proper installation, care and maintenance are
essential for maximum performance and trouble-free
operation of your equipment.

• Visit our website www.manitowocice.com for manual
updates, translations, or contact information for
service agents in your area.

• This equipment contains high voltage electricity and
refrigerant charge. Installation and repairs are to be
performed by properly trained technicians aware of
the dangers of dealing with high voltage electricity
and refrigerant under pressure. The technician must
also be certified in proper refrigerant handling
and servicing procedures. All lockout and tag out
procedures must be followed when working on this
equipment.

• This equipment is intended for indoor use only. Do
not install or operate this equipment in outdoor
areas.

• As you work on this equipment, be sure to pay close
attention to the safety notices in this handbook.
Disregarding the notices may lead to serious injury
and/or damage to the equipment.

Warning

n

Follow these electrical requirements during
installation of this equipment.

• All field wiring must conform to all applicable
codes of the authority having jurisdiction. It is
the responsibility of the end user to provide the
disconnect means to satisfy local codes. Refer to
rating plate for proper voltage.

• This appliance must be grounded.

• This equipment must be positioned so that
the plug is accessible unless other means for
disconnection from the power supply (e.g., circuit
breaker or disconnect switch) is provided.

• Check all wiring connections, including factory
terminals, before operation. Connections can
become loose during shipment and installation.

• For a cord-connected appliance, the following must
be included:

• Do not unplug by pulling on cord. To unplug,

grasp the plug, not the cord.

• Unplug from outlet when not in use and before

servicing or cleaning.

• Do not operate any appliance with a

damaged cord or plug, or after the appliance
malfunctions or is dropped or damaged in any
manner. Contact the nearest authorized service
facility for examination, repair, or electrical or
mechanical adjustment

Warning

n

Follow these precautions to prevent personal
injury during installation of this equipment:

• Installation must comply with all applicable
equipment fire and health codes with the authority
having jurisdiction.

• To avoid instability the installation area must be
capable of supporting the combined weight of
the equipment and product. Additionally the
equipment must be level side to side and front to
back.

• Ice machines require a deflector when installed on
an ice storage bin. Prior to using a non-OEM ice
storage system with this ice machine, contact the
bin manufacturer to assure their ice deflector is
compatible.

• Remove all removable panels before lifting and
installing and use appropriate safety equipment
during installation and servicing. Two or more
people are required to lift or move this appliance to
prevent tipping and/or injury.

• Do not damage the refrigeration circuit when
installing, maintaining or servicing the unit.

• Connect to a potable water supply only.

• This equipment contains refrigerant charge.

• Installation of the line sets must be performed by
a properly trained and EPA certified refrigeration
technician aware of the dangers of dealing with
refrigerant charged equipment.

Warning

n

Follow these precautions to prevent personal
injury while operating or maintaining this
equipment.

• Legs or casters must be installed and the legs/
casters must be screwed in completely. When
casters are installed the mass of this unit will allow
it to move uncontrolled on an inclined surface.
These units must be tethered/secured to comply
with all applicable codes. Swivel casters must be
mounted on the front and rigid casters must be
mounted on the rear. Lock the front casters after
installation is complete.

• Some 50 Hz models may contain up to 150 grams
of R290 (propane) refrigerant. R290 (propane)
is flammable in concentrations of air between
approximately 2.1% and 9.5% by volume (LEL lower
explosion limit and UEL upper explosion limit). An
ignition source at a temperature higher than 470°C
is needed for a combustion to occur.

• Refer to nameplate to identify the type of
refrigerant in your equipment.

• Only trained and qualified personnel aware of the
dangers are allowed to work on the equipment.

• Read this manual thoroughly before operating,
installing or performing maintenance on the
equipment. Failure to follow instructions in this
manual can cause property damage, injury or
death.

• Crush/Pinch Hazard. Keep hands clear of moving
components. Components can move without
warning unless power is disconnected and all
potential energy is removed.

• Moisture collecting on the floor will create a
slippery surface. Clean up any water on the floor
immediately to prevent a slip hazard.

Warning

n

Follow these precautions to prevent personal
injury while operating or maintaining this
equipment.

• Objects placed or dropped in the bin can affect
human health and safety. Locate and remove any
objects immediately.

• Never use sharp objects or tools to remove ice or
frost.

• Do not use mechanical devices or other means to
accelerate the defrosting process.

• When using cleaning fluids or chemicals, rubber
gloves and eye protection (and/or face shield) must
be worn.

DANGER

Do not operate equipment that has been misused,
abused, neglected, damaged, or altered/modified
from that of original manufactured specifications.
This appliance is not intended for use by persons
(including children) with reduced physical, sensory
or mental capabilities, or lack of experience
and knowledge, unless they have been given
supervision concerning use of the appliance
by a person responsible for their safety. Do not
allow children to play with, clean or maintain this
appliance without proper supervision.

DANGER

Follow these precautions to prevent personal
injury during use and maintenance of this
equipment:

• It is the responsibility of the equipment owner to
perform a Personal Protective Equipment Hazard
Assessment to ensure adequate protection during
maintenance procedures.

• Do Not Store Or Use Gasoline Or Other Flammable
Vapors Or Liquids In The Vicinity Of This Or Any
Other

• Appliance. Never use flammable oil soaked cloths
or combustible cleaning solutions for cleaning.

• All covers and access panels must be in place and
properly secured when operating this equipment.

• Risk of fire/shock. All minimum clearances must be
maintained. Do not obstruct vents or openings.

• Failure to disconnect power at the main power
supply disconnect could result in serious injury or
death. The power switch DOES NOT disconnect all
incoming power.

• All utility connections and fixtures must be
maintained in accordance with the authority
having jurisdiction.

• Turn off and lockout all utilities (gas, electric,
water) according to approved practices during
maintenance or servicing.

• Units with two power cords must be plugged
into individual branch circuits. During movement,
cleaning or repair it is necessary to unplug both
power cords.

We reserve the right to make product improvements at
any time. Specifications and design are subject to change
without notice.

Table of Contents

General Information

Model Numbers............................... 15

How to Read a Model Number ................ 16

Ice Machine Warranty Information............ 17

Installation

Location of Ice Machine....................... 18

Ice Machine Clearance Requirements......... 19

Ice Machine Heat of Rejection ................ 19

Leveling the Ice Machine......................20

Electrical Requirements....................... 21

Electrical Specifications....................... 22

Water Service/Drains .........................24

Water Supply.............................. 24

Water Inlet Lines ..........................24

Drain Connections ........................ 25

Cooling Tower Applications ................ 25

Water Supply and Drain Line Sizing/

Connections .............................. 26

Part Number STH042 4/16 9

Maintenance

Interior Cleaning and Sanitizing ..............27

General ................................... 27

Cleaning and Sanitizing Procedure......... 27

Touch Pad Operation ...................... 28

Remove Parts for Cleaning................. 32

Preventative Maintenance Cleaning .......... 37

Ice Machine Inspection ....................... 38

Cleaning the Condenser ......................39

Removal from Service/Winterization .........40

Bin Removal ..................................41

Operation

Touch Pad Features ...........................43

On/Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Delay ..................................... 44

Clean ..................................... 44

Bin Full.................................... 45

Service.................................... 45

Ice Making Sequence of Operation ...........46

Control Board Timers ...................... 49

Safety Limits .............................. 50

Energized Parts Chart...................... 52

Operational Checks ...........................54

Ice Thickness Check ....................... 54

Ice Thickness Adjustment ..................54

Minimum/Maximum Slab weight .......... 55

10 Part Number STH042 4/16

Troubleshooting

Problem Checklist ............................ 57

Control Board Test Mode...................... 59

Operating Ice Machine with Bin and Touch Pad

Removed .................................59

Diagnosing an Ice Machine that Will Not Run . 60
Ice Machine Does Not Cycle Into Harvest when
Water Loses Contact with the Harvest Float

Switch......................................... 61

Ice Machine Cycles Into Harvest Before Water
Loses Contact with the Harvest Float Switch.. 63

Ice Production Check .........................65

Installation/Visual Inspection Checklist ...... 67

Water System Checklist ....................... 68

Ice Formation Pattern .........................69

Safety Limit Feature ..........................71

Analyzing Discharge Pressure ................ 78

Analyzing Suction Pressure ..................80

Harvest Valve .................................84

Comparing Evaporator Inlet/Outlet

Temperatures ................................. 88

Discharge Line Temperature Analysis......... 89

Refrigeration Component Diagnostics........ 91

Refrigeration Component Diagnostic Chart ..94

Part Number STH042 4/16 11

Component Check Procedures

Main Fuse .....................................99

Bin Switch....................................100

Touch Pad ....................................102

Float Switch..................................104

Water Trough Thermistor ....................106

Compressor Electrical Diagnostics...........108

Fan Cycle Control ............................110

High Pressure Cutout (HPCO) Control........111

Filter-Driers ..................................112

Refrigerant Recovery/Evacuation............113

Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

Refrigerant Re-use Policy .................114

Recovery and Recharging Procedures ....116

System Contamination Cleanup .............119

Determining Severity of Contamination...119
Mild System Contamination Cleanup

Procedure................................121

Severe System Contamination Cleanup

Procedure................................122

Replacing Pressure Controls without

Removing Refrigerant Charge.............123

Total System Refrigerant Charge.............125

12 Part Number STH042 4/16

Charts

Cycle Times, 24 Hr. Ice Production and

Refrigerant Pressure Charts..................127

U0140 Self-contained Air-cooled..........128

U0140 Self-contained Water-cooled.......129

U0190 Self-contained Air-cooled..........130

U0240 Self-contained Air-cooled..........131

U0240 Self-contained Water-cooled.......132

U0310 Self-contained Air-cooled..........133

U0310 Self-contained Water-cooled.......133

Diagrams

Wiring Diagrams .............................135

U140/U190/U240 wiring diagram

Without J4 thermistor terminal ...........136

U310 wiring diagram

Without J4 thermistor terminal ...........137

U140/U190/U240 wiring diagram

With J4 thermistor terminal...............138

U310 wiring diagram

With J4 thermistor terminal...............139

Electronic Control Board with J4 thermistor

terminal..................................140

Electronic Control Board with J1 and without

J4 Thermistor terminal ...................141

Electronic Control Board Prior to J1 the

terminal..................................142

Tubing Schematic - U0140 ...................143

Tubing Schematic - U0190/U0240/U0310....143

Part Number STH042 4/16 13

THIS PAGE INTENTIONALLY LEFT BLANK

14 Part Number STH042 4/16

General Information

Model Numbers

This manual covers the following models:

Self-contained

Air-cooled

UD0140A UD0140W

UD0140AE UD0140WE

UY0140A UY0140W

UY0140AE UY0140WE

UR0140A –

UR0140AE –

UD0190A –

UD0190AE –

UY0190A –

UY0190AE –

UR0190A –

UR0190AE –

UD0240A UD0240W

UD0240AE UD0240WE

UY0240A UY0240W

UY0240AE UY0240WE

UR0240A –

UR0240AE –

UD0310A UD0310W

UD0310AE UD0310WE

UY0310A UY0310W

UY0310AE UY0310WE

UR0310A –

UR0310AE –

Self-contained

Water-cooled

Part Number STH042 4/16 15

How to Read a Model Number

Cube Size

Series

Capacity

Condenser

Typ e

U D 0140 A E

E - WRAS 50Hz

R - Regular
D - Dice
Y - Half-dice

An ice machine contains high voltage electricity and
refrigerant charge. Repairs are to be performed by
properly trained refrigeration technicians aware of
the dangers of dealing with high voltage electricity
and refrigerant under pressure.

A - Air-cooled
W - Water-cooled

Warning

n

16 Part Number STH042 4/16

Ice Machine Warranty Information

For warranty information visit:

http://www.kool-aire.com/Service/Warranty

• Warranty Verification

• Warranty Registration

• View and download a copy of the warranty Owner
Warranty Registration Card

Warranty coverage begins the day the ice machine is
installed.

Part Number STH042 4/16 17

Installation

Location of Ice Machine

The location selected for the ice machine must meet
the following criteria. If any of these criteria are not met,
select another location.

• The location must be indoors.

• The location must be free of airborne and other
contaminants.

• Air temperature: Must be at least 40°F (4°C) but must
not exceed 110°F (43.4°C).

• The location must not be near heat-generating
equipment or in direct sunlight.

• The location must be capable of supporting the
weight of the ice machine and a full bin of ice.

• The location must allow enough clearance for water,
drain, and electrical connections in the rear of the
ice machine.

• The location must not obstruct airflow through or
around the ice machine (condenser airflow is in and
out the front). Refer to the chart below for clearance
requirements.

• The ice machine must be protected if it will be
subjected to temperatures below 32°F (0°C). Failure
caused by exposure to freezing temperatures is not
covered by the warranty.

Ice Machine Clearance Requirements

Self-contained

Air-cooled

Top/Sides 5" (127 mm)* 5" (127 mm)*

Back 5" (127 mm)* 5" (127 mm)*

*The ice machine may be built into a cabinet.

There is no minimum clearance requirement for the top
or left and right sides of the ice machine. The listed values
are recommended for efficient operation and servicing
only.

Self-contained

Water-cooled

Ice Machine Heat of Rejection

Series

Ice Machine

U140 2400 2900
U190 2200 2600
U240 2400 3400
U310 3800 6000

* B.T.U./Hour
** Because the heat of rejection varies during the ice making

cycle, the figure shown is an average.

Ice machines, like other refrigeration equipment, reject
heat through the condenser. It is helpful to know the
amount of heat rejected by the ice machine when sizing
air conditioning equipment where self-contained air­cooled ice machines are installed.

Heat of Rejection*

Air Conditioning** Peak

Part Number STH042 4/16 19

Leveling the Ice Machine

1. Screw the leveling legs onto the bottom of the ice
machine.

2. Screw the foot of each leg in as far as possible.

Caution

,

The legs must be screwed in tightly to prevent them
from bending.

3. Move the ice machine into its final position.

4. Level the ice machine to ensure that the siphon
system functions correctly. Use a level on top of the
ice machine. Turn each foot as necessary to level the
ice machine from front to back and side to side.

THREAD
LEVELING LEG
INTO BASE OF

CABINET

THREAD “FOOT”

IN AS FAR AS

POSSIBLE

SV1606

Leg Installation

20 Part Number STH042 4/16

Electrical Requirements

Voltage

The maximum allowable voltage variation is ±10% of the
rated voltage on the ice machine model/serial number
plate at start-up (when the electrical load is highest).

Fuse/Circuit Breaker

A separate fuse/circuit breaker must be provided for each
ice machine.

Total Circuit Ampacity

The total circuit ampacity is used to help select the wire
size of the electrical supply.

The wire size (or gauge) is also dependent upon
location, materials used, length of run, etc., so it must be
determined by a qualified electrician.

Part Number STH042 4/16 21

Electrical Specifications

Air-cooled Ice Machine

Ice Machine

U140

U190

U240

U310

Voltage

Phase Cycle

115/1/60 15 5.0

208-230/1/60 15 2.5

230/1/50 15 2.5
115/1/60 15 6.0

208-230/1/60 15 2.5

230/1/50 15 2.5
115/1/60 15 7.0

208-230/1/60 15 4.0

230/1/50 15 4.0
115/1/60 15 10.0

208-230/1/60 15 4.5

230/1/50 15 4.5

Max. Fuse/

Circuit

Breaker

Total Amps

22 Part Number STH042 4/16

Water-cooled Ice Machine

Max. Fuse/

Circuit

Breaker

Warning

Total Amps

Ice Machine

U140

U240

U310

Voltage

Phase Cycle

115/1/60 15 5.0

208-230/1/60 15 2.5

230/1/50 15 2.5
115/1/60 15 7.0

208-230/1/60 15 4.0

230/1/50 15 4.0
115/1/60 15 10.0

208-230/1/60 15 4.5

230/1/50 15 4.5

n

All wiring must conform to local, state and national
codes.

Warning

n

The ice machine must be grounded in accordance
with national and local electrical code.

Part Number STH042 4/16 23

Water Service/Drains

WATER SUPPLY

Local water conditions may require treatment of the
water to inhibit scale formation, filter sediment, and
remove chlorine odor and taste.

Important

If you are installing a Manitowoc water filter system,
refer to the Installation Instructions supplied with the
filter system for ice making water inlet connections.

Warning

n

For ice making, connect to a potable water supply
only.

WATER INLET LINES

Follow these guidelines to install water inlet lines:

• Do not connect the ice machine to a hot water
supply. Be sure all hot water restrictors installed for
other equipment are working. (Check valves on sink
faucets, dishwashers, etc.)

• If water pressure exceeds the maximum
recommended pressure, 80 psig (5.5 bar) obtain
a water pressure regulator from your Manitowoc
distributor.

• Install a water shut-off valve for ice making potable
water.

• Insulate water inlet lines to prevent condensation.

24 Part Number STH042 4/16

DRAIN CONNECTIONS

Follow these guidelines when installing drain lines
to prevent drain water from flowing back into the ice
machine and storage bin:

• Drain lines must have a 1.5-inch drop per 5 feet of run
(2.5 cm per meter), and must not create traps.

• The floor drain must be large enough to
accommodate drainage from all drains.

• Install a tee to vent the ice machine drain to the
atmosphere.

• Insulate drain lines to prevent condensation.

COOLING TOWER APPLICATIONS

Water Cooled Models Only

A water-cooling tower installation does not require
modification of the ice machine. The water regulator
valve for the condenser continues to control the
refrigeration discharge pressure.

It is necessary to know the amount of heat rejected, and
the pressure drop through the condenser and water
valves (inlet to outlet) when using a cooling tower on an
ice machine.

• Water entering the condenser must not exceed 90°F
(32.2°C).

• Water flow through the condenser must not exceed 5
gallons (19 liters) per minute.

• Allow for a pressure drop of 7 psig (.48 bar) between
the condenser water inlet and the outlet of the ice
machine.

• Water exiting the condenser must not exceed 110°F
(43.3°C).

Caution

,

Plumbing must conform to state and local codes.

Part Number STH042 4/16 25

WATER SUPPLY AND DRAIN LINE SIZING/
CONNECTIONS

U310 only

inside diameter

Machine Fitting

3/8" (9.5 mm) min.

Tubing Size Up to Ice

Ice Machine Fitting

3/8” Female Pipe Thread

Water

Pressure

inside diameter

3/8" (9.5 mm) min.

U310 only

3/8” Female Pipe Thread

inside diameter

1/2” (12.7 mm) min.

1/2” Female Pipe Thread

1/2” Female Pipe Thread

inside diameter

1/2” (12.7 mm) min.

20 psi (138 kPa) min.

Water

Temperature

40°F (4°C) min.

Location

Ice Making

26 Part Number STH042 4/16

80 psi (550 kPa) max.

90°F (32°C) max.

Water Inlet

20 psi (1.38 bar) min.

150 psi (10.3 bar) max.

— — 3/8” Female Pipe Thread

40°F (4°C) min.

90°F (32°C) max

Condenser

Water Inlet

Bin Drain --- --- 1/2” Female Pipe thread

Condenser

Water Drain

Maintenance

Interior Cleaning and Sanitizing

GENERAL

Clean and sanitize the ice machine every six months
for efficient operation. If the ice machine requires
more frequent cleaning and sanitizing, consult a
qualified service company to test the water quality and
recommend appropriate water treatment.

The ice machine must be taken apart for cleaning and
sanitizing.

Caution

,

Use only Manitowoc approved Ice Machine Cleaner
and Sanitizer. It is a violation of Federal law to use
these solutions in a manner inconsistent with their
labeling. Read and understand all labels printed on
bottles before use.

CLEANING AND SANITIZING PROCEDURE

Ice machine cleaner is used to remove lime scale and
mineral deposits. Ice machine sanitizer disinfects and
removes algae and slime.

Part Number STH042 4/16 27

TOUCH PAD OPERATION

Pressing and holding the clean button for 3 seconds
starts the clean cycle. The Clean & On/Off lights energize
indicating the clean cycle has started and ice making will
automatically start when the Clean cycle is complete.

• Setting the ice machine to stop after the clean
cycle: Press the On/Off button. The On/Off light will
de-energize indicating the ice machine will stop after
the clean cycle.

• Pausing the cleaning cycle: Press the Clean button.
The clean light will flash indicating the clean cycle has
paused. Pressing the Clean button again will restart
the clean cycle.

Step 1 Press the On/Off button after ice falls from the
evaporator at the end of a Harvest cycle. Or, press the On/
Off button and allow the ice to melt off the evaporator.

Caution

,

Never use anything to force ice from the evaporator.
Damage may result.

Step 2 Remove all ice from the bin.

Warning

n

Wear rubber gloves and safety goggles (and/or
face shield) when handling Ice Machine Cleaner or
Sanitizer.

28 Part Number STH042 4/16

Caution

,

Do not mix Ice Machine Cleaner and Sanitizer
solutions together. It is a violation of Federal law to
use these solutions in a manner inconsistent with
their labeling.

Step 3 To start a cleaning cycle, press the Clean
button. Water will flow through the water dump valve
and down the drain. Wait until the water trough refills,
then add the proper amount of ice machine cleaner to
the water trough.

Model Amount of Cleaner

U0140 2 ounces (60 ml)
U0190 5 ounces (150 ml)
U0240 5 ounces (150 ml)
U0310 5 ounces (150 ml)

Wait until the clean cycle is complete (approximately 22
minutes) then press the On/Off button and disconnect
power and water supplies to the ice machine.

Step 4 Remove parts for cleaning.
Refer to the proper parts removal for your machine.
Continue with step 5 when the parts have been removed.

Part Number STH042 4/16 29

Step 5 Mix a solution of cleaner and warm water.
Depending on the amount of mineral buildup, a larger
quantity of solution may be required. Use the ratio in the
table below to mix enough solution to thoroughly clean
all parts.

Solution Type Water Mixed with

Cleaner 1 gal. (4 l) 16 oz (500 ml) cleaner

Caution

,

Do not immerse electrical connectors or motors
for any components in water, cleaner or sanitizer
solutions.

Use half of the cleaner/water solution to clean all
components. The cleaner solution will foam when it
contacts lime scale and mineral deposits; once the
foaming stops use a soft bristle brush, sponge or cloth
(not a wire brush) to carefully clean the parts. Soak the
parts for 5 minutes (15 – 20 minutes for heavily scaled
parts). Rinse all components with clean water.

Step 6 While components are soaking, use half of the
cleaner/water solution to clean all foodzone surfaces of
the ice machine and bin. Use a nylon brush or cloth to
thoroughly clean the following ice machine areas:

• Evaporator plastic parts – including top, bottom and
sides

• Bin bottom, sides and top

• Rinse all areas thoroughly with clean water.

30 Part Number STH042 4/16

Step 7 Mix a solution of sanitizer and warm water.

Solution Type Water Mixed With

Sanitizer 3 gal. (12 l) 2 oz (60 ml) sanitizer

Use half of the sanitizer/water solution to sanitize all
removed components. Use a spray bottle to liberally
apply the solution to all surfaces of the removed parts or
soak the removed parts in the sanitizer/water solution.
Do not rinse parts after sanitizing.

Step 8 Use half of the sanitizer/water solution to
sanitize all foodzone surfaces of the ice machine and bin.
Use a spray bottle to liberally apply the solution. When
sanitizing, pay particular attention to the following areas:

• Evaporator plastic parts - including top, bottom and
sides

• Bin bottom, sides and top

Do not rinse the sanitized areas.

Step 9 Replace all removed components, wait

10 minutes, then reapply power and water to the ice
machine

Step 10 Press the Clean button. Water will flow through
the water dump valve and down the drain. Wait until the
water trough refills, then add the proper amount of ice
machine sanitizer to the water trough.

Model Amount of Sanitizer

U0140 1 ounces (30 ml)
U0190 2 ounces (60 ml)
U0240 2 ounces (60 ml)
U0310 2 ounces (60 ml)

Wait until the sanitize cycle is complete (approximately
22 minutes) then press the Ice button to start ice making.

Part Number STH042 4/16 31

REMOVE PARTS FOR CLEANING

Warning

n

Disconnect electric power to the ice machine at the
electric switch box before proceeding.

1. Remove the Harvest Float Switch and Ice Thickness
Float Switch

• Pull forward on the bottom of the bracket until

clear of the tab, then slide bracket upward to
remove the bracket and float as an assembly.
At this point, the float switches can easily be
cleaned. If complete removal is desired, follow
the wires to the bulkhead grommet (exit point)
in the back wall. Pull the wire connector through
the bulkhead grommet, then disconnect the wire
leads from the connector.

NOTE: The wire from the top grommet goes to the ice
thickness float switch (front switch). The wire from the
bottom grommet goes to the Harvest float switch (side
switch).

Important

Reversing the mounting location of the ice thickness and
the harvest floats will result in a safety limit 2 failure.

• The ice thickness float must be mounted to the front
of the water trough and the electrical connection
must be in the top bulkhead grommet.

• The harvest float must be mounted to the side of the
water trough and the electrical connection must be
in the bottom bulkhead grommet.

• The wire connectors for each float are different
and will not allow incorrect electrical bulkhead
connection.

32 Part Number STH042 4/16

WIRE CONNECTORS ARE LOCATED BEHIND BULKHEAD

PULL THROUGH GROMMET TO DISCONNECT

HARVEST FLOAT

SWITCH & BRACKET

DISCONNECT WIRES

FOR COMPLETE

ICE THICKNESS FLOAT

SWITCH & BRACKET

REMOVAL

Part Number STH042 4/16 33

2. Remove the Water Trough Thermistor and Water
Trough

• Remove the upper thumbscrew.

• While supporting the water trough remove the

thumbscrew and thermistor.

• While supporting the water trough remove

the lower thumbscrew from beneath the water
trough.

• Remove the water trough from the bin area.

UPPER THUMBSCREW LOWER THUMBSCREW

34 Part Number STH042 4/16

3. Remove the Ice Damper

• Remove thumbscrew from bin switch cover.

• Support ice damper and then pull bin switch
cover and ice damper forward to remove.

1. REMOVE THUMBSCREW

2. SUPPORT ICE DAMPER THEN

SLIDE RIGHT SIDE FORWARD TO REMOVE

Part Number STH042 4/16 35

4. Remove the Water Distribution Tube

• Distribution tube thumbscrews are retained to
prevent loss. Loosen thumbscrews but do not
pull thumbscrews out of distribution tube.

• Loosen the two outer screws and pull forward on
the distribution tube to release.

NOTE: For ease of assembly when reinstalling the water
distribution tube, install the top edge first.

1. LOOSEN THUMBSCREWS

2. PULL DISTRIBUTION TUBE
FORWARD TO REMOVE

36 Part Number STH042 4/16

Preventative Maintenance Cleaning

This cleaning procedure can be performed between the
bi-annual cleaning and sanitizing cycles. This procedure
does not require removing the ice from the bin.

Step 1 Press the On/Off button after ice falls from the
evaporator at the end of a Harvest cycle. Or, press the On/
Off button and allow the ice to melt off the evaporator.

Caution

,

Never use anything to force ice from the evaporator.
Damage may result.

Warning

n

Wear rubber gloves and safety goggles (and/or
face shield) when handling Ice Machine Cleaner or
Sanitizer.

Step 2 To start a cleaning cycle, press the Clean
button. Water will flow through the water dump valve
and down the drain. Wait until the water trough refills,
then add the proper amount of ice machine cleaner to
the water trough.

Model Amount of Cleaner

U0140 2 ounce (60 ml)
U0190 5 ounces (150 ml)
U0240 5 ounces (150 ml)
U0310 5 ounces (150 ml)

Wait until the clean cycle is complete (approximately 22
minutes) then press the On/Off button.

Part Number STH042 4/16 37

Ice Machine Inspection

Check all water fittings and lines for leaks. Also, make
sure the refrigeration tubing is not rubbing or vibrating
against other tubing, panels, etc.

Do not put anything (boxes, etc.) in front of the ice
machine. There must be adequate airflow through and
around the ice machine to maximize ice production and
ensure long component life.

Exterior Cleaning

Clean the area around the ice machine as often as
necessary to maintain cleanliness and efficient operation.

Sponge any dust and dirt off the outside of the ice
machine with mild soap and water. Wipe dry with a clean,
soft cloth.

Cleanup any fallen ice or water spills as they occur.

38 Part Number STH042 4/16

Cleaning the Condenser

General

Warning

n

Disconnect electric power to the ice machine head
section and the remote condensing unit at the electric
service switches before cleaning the condenser.

A dirty condenser restricts airflow, resulting in excessively
high operating temperatures. This reduces ice production
and shortens component life.

• Clean the condenser at least every six months.

Warning

n

The condenser fins are sharp. Use care when cleaning
them.

• Shine a flashlight through the condenser to check for
dirt between the fins.

• Blow compressed air or rinse with water from the
inside out (opposite direction of airflow).

Part Number STH042 4/16 39

Removal from Service/Winterization

1. Clean and sanitize the ice machine.

2. Press the On/Off button to turn off the ice machine.

3. Turn off the water supply, disconnect and drain the
incoming ice-making water line at the rear of the ice
machine and drain the water trough.

4. Energize the ice machine, wait one minute for the
water inlet valve to open and blow compressed air in
both the incoming water and the drain openings in
the rear of the ice machine to remove all water.

5. Press the On/Off button and disconnect the electric
power at the circuit breaker or the electric service
switch.

6. Fill spray bottle with sanitizer and spray all interior
food zone surfaces. Do not rinse and allow to air dry.

7. Replace all panels.

40 Part Number STH042 4/16

Bin Removal

1. Disconnect power.

2. Remove all ice from bin.

3. Remove air filter and louver from lower front of
machine.

4. Loosen screws and rotate clips to release bin from
base.

5. Disconnect clamp and remove bin drain.

6. Remove control box panel.

7. Remove communication cable from control board.

8. Remove rear cover.

9. Slide bin forward to remove.

NOTE: When reinstalling the bin, ensure the bin seal is
in place and is not pinched/folded as it mates to the
cabinet. A watertight seal is required to prevent future
condensation or water leakage from entering the ice
machine base.

DISCONNECT CLAMP

AND REMOVE BIN DRAIN

SCREWS AND PLATES

DISCONNECT COMMUNICATION

Part Number STH042 4/16 41

CABLE

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42 Part Number STH042 4/16

Operation

Touch Pad Features

The touch pad offers a series of pressure sensitive buttons
to control ice machine operation and provide operational
status.

On/Off - Blue = Machine On
Off = Machine Is Off

Delay - Blue = Delay Mode On
Off = Delay Mode Is Off

Clean - Yellow = Clean Cycle On
Off = Cleaning is Off
Flashing = Cleaning Is Paused

Bin Full - Blue = Bin Is Full
Off = Bin Is Not Full

Service - Red = Needs Service
Off = Doesn’t Need Service

ON/OFF

The On/Off Button is used to start and stop ice making.
The blue light indicates whether the ice machine is in Ice
Making (light on) or Off (light off ).

NOTE: Stopping and restarting a freeze cycle with ice on
the evaporator will result in a thick bridge and larger than
normal cubes; or result in an ice slab that will not release
from the evaporator.

Part Number STH042 4/16 43

DELAY

Pressing the Delay button will start a delay period. The ice
machine will finish the freeze and harvest cycle and then
start the delay period.

• Pressing the button once will start a 4 hour delay
period.

• Pressing the button twice will start a 12 hour delay
period.

• Pressing the button three times will start a 24 hour
delay period.

• Pressing the button four times will cancel the delay
periods.

NOTE: The delay period will be canceled if power is
interrupted to the ice machine. When power is restored,
the ice machine will start an ice making cycle.

CLEAN

Pressing the Clean button for 3 seconds will start a clean
cycle. After the clean cycle is complete, the ice machine
will automatically start an ice making cycle.

• Pressing the Clean button again within 45seconds of
the clean cycle starting will abort the clean cycle.

• Pressing the On/Off button after 45 seconds will
pause the Clean cycle. The On/Off light will flash
on/off to indicate pause mode. Pressing the On/Off
button again will continue the Clean cycle from the
point of interruption.

• Pressing the control board test button anytime
during the clean cycle will cancel the clean cycle.

• Opening the damper for 30 seconds during the clean
cycle will start and automatic shutdown sequence.

44 Part Number STH042 4/16

BIN FULL

The Bin Full light energizes when the bin is full or is de­energized if the bin is not full.

SERVICE

The service light indicates the machine needs attention.

• Refer to safety limits if this light is energized.

Part Number STH042 4/16 45

Ice Making Sequence of Operation

NOTE: To date there are two main revisions to the
sequence of operation.

1. Software version 2.58 and higher have a 25 second
water pump delay in the freeze cycle.

2. Control boards with a J4 terminal can utilize a
thermistor to control when the water pump delay
occurs in the freeze cycle.

WITH WATER TROUGH THERMISTOR

The following sequence occurs in the freeze cycle:

• When the temperature of the water reaches 34° F the
water pump de-energizes for 25 seconds,
then re energizes.

• When the water pump restarts the water inlet
solenoid energizes for 7 seconds.

WITHOUT WATER TROUGH THERMISTOR

The following sequence occurs in the freeze cycle:

• At 3.75 minutes the water pump de-energizes for 25
seconds, then re-energizes.

• When the water pump restarts the water inlet
solenoid energizes for 7 seconds.

46 Part Number STH042 4/16

The On/Off button must be depressed and the ice
damper must be closed before the ice machine will start.

Water Purge Cycle

The ice machine purges any remaining water from the
water trough down the drain.

Freeze Cycle

Prechill - The refrigeration system chills the evaporator
before water flow over the evaporator starts. The water
inlet valve energizes during the pre-chill and remains on
until the ice thickness float switch is satisfied.

Freeze - Water flowing across the evaporator cools as
the freeze cycle progresses. (Software version 2.58 or
higher: The water pump turns off for 25 seconds and the
water inlet valve energizes for 7 seconds when the pump
restarts) Water flowing across the evaporator will start to
freeze and build ice on the evaporator. After a sheet of ice
has formed, the harvest float switch signals the control
board to start a harvest cycle.

Harvest Cycle

Any remaining water is purged down the drain as
refrigerant gas warms the evaporator. When the
evaporator warms, the sheet of cubes slides off the
evaporator and into the storage bin. If all cubes fall clear
of the ice damper the ice machine starts another freeze
cycle. The maximum harvest time is a total of 7 minutes.
If the bin switch does not activate within 3.5 minutes, the
harvest cycle extends another 3.5 minutes.

Full Bin Cycle

If the ice damper is held open by ice cubes the ice
machine shuts off. When the ice damper closes the ice
machine starts a new cycle at the water purge.

Part Number STH042 4/16 47

Water Assist Harvest Cycle

The maximum harvest time is a total of 7 minutes.
If the bin switch does not activate within 7 minutes a
water assist harvest cycle initiates using the following
sequence:

1. The compressor de-energizes.

2. The water inlet valve energizes and fills the water
trough.

3. The water pump energizes for 2 minutes and
circulates water over the evaporator.

If the bin switch did not open & close.

4. The water dump valve energizes and drains water
from the water trough.

5. Step 1 through 4 repeat.

6. A freeze cycle starts.

NOTE: If the bin switch opens & closes anytime during the
cycle the ice machine starts a new freeze cycle.

• The maximum water fill time for the water assist
harvest is 105 seconds.

48 Part Number STH042 4/16

CONTROL BOARD TIMERS

• The ice machine is locked into the freeze cycle for 6
minutes before a harvest cycle can be initiated.

• The freeze time lock in feature is bypassed on the
initial cycle (manual start or after a full bin/safety limit
condition).

• If the harvest float switch is in the down position for
10 continuous seconds during the start of a freeze
cycle, a harvest sequence is initiated.

• The maximum freeze time is 45 minutes at which
time the control board automatically initiates a
harvest sequence.

• The maximum harvest time is a total of 7 minutes.
If the bin switch does not activate within 3.5 minutes,
the harvest cycle extends another 3.5 minutes. If 7
minutes is exceeded a Harvest Assist Cycle starts.

• The water fill valve is de-energized 1 minute after the
freeze cycle starts. The control board will energize the
water inlet valve one more times 3 minutes into the
freeze cycle.

Control boards with firmware version 2.58 or larger

• The control board will stop the ice machine for 25
seconds during the freeze cycle and then re-energize.

Part Number STH042 4/16 49

SAFETY LIMITS

Safety limits are stored and indicated by the control
board. The number of cycles required to stop the ice
machine varies for each safety limit.

Safety limits can be reset by pressing the On/Off button
and starting a new ice making cycle.

A safety limit shutdown is indicated by the red Service
light on the touch pad.

Safety Limit 1

If the freeze time reaches 45 minutes, the control board
automatically initiates a harvest cycle.

• After 3 consecutive 45 minute cycles control board
light SL#1 along with the touch pad Service (wrench)
light will flash on/off at 1 second intervals.

• If 6 consecutive 45-minute freeze cycles occur, the
ice machine stops and the SL#1 light on the control
board and the Service (wrench) light on the touch
pad will be on continuously.

Safety Limit 2

• If the harvest time reaches 3.5 minutes, the control
board automatically energizes the water pump and
extends the harvest cycle another 3.5 minutes (7
minutes total).

• If the ice damper does not open and close within the
7 minute harvest cycle the ice machine enters a water
thaw cycle for 170 seconds.

• If the damper does not open/close within the 170
second thaw cycle, a second thaw cycle starts.

• The control board automatically initiates a freeze
sequence when the thaw cycle(s) is complete.

• If 3 consecutive 7 minute harvest/thaw cycles occur,
the ice machine stops.

50 Part Number STH042 4/16

Safety Limit 3

If the freeze time reaches 4 minutes and water is not
sensed (float remains down for 10 continuous seconds)
the ice machine stops.

• Safety Limit 3 is bypassed on the initial cycle (manual
start or after a full bin/safety limit condition). For
all subsequent cycles if the freeze time reaches 4
minutes and water is not sensed, the ice machine
stops and initiates a 30 minute delay period. Control
board lights SL#1 and SL#2 along with the touch pad
Service (wrench) light will flash on/off at 1 second
intervals.

• The ice machine automatically restarts at the end of
the 30 minute delay period and stops flashing the
control board and Service (wrench) lights.

• If 100 consecutive failures occur the ice machine
stops and the touch pad Service (wrench) light
remains energized.

Part Number STH042 4/16 51

Length of Time

Ice Thickness

Float Switch

20 seconds

5 seconds

60 Seconds

Until Harvest

Float Switch

CLOSED

closes for 10

continual seconds

THEN OPEN

Harvest

Float Switch

Fan Motor *

Compressor

& Condenser

Valve

Dump

Valve

Water Inlet

Valve

Harvest

OFF ON OFF ON OFF CLOSED CLOSED

Initial Start-up

1. Water purge

OFF ON OFF OFF ON CLOSED CLOSED

2. Refrigeration

Pump

Water

OPERATION

ICE MAKING

Self-Contained Ice Machines

SEQUENCE OF

ENERGIZED PARTS CHART

52 Part Number STH042 4/16

System Start-up

OFF OFF ON OFF ON OPEN CLOSED

Freeze

Sequence

3. Pre chill

CLOSED

OPEN THEN

ON** OFF ON ** OFF ON

4. Freeze

Length of Time

Float Switch

Ice Thickness

Harvest

Float Switch

Compressor

& Condenser

Fan Motor *

20 seconds

ON CLOSED CLOSED

Bin switch

activation

re-closes

Until bin switch

Dump

ON

Valve

FOR 20

THEN

SECONDS

OFF

Valve

Water Inlet

Valve

Harvest

Pump

Water

OPERATION

ICE MAKING

SEQUENCE OF

Harvest

OFF ON OFF

Sequence

5. Water Purge

OFF*** ON OFF*** OFF*** ON CLOSED CLOSED

6. Harvest

OFF OFF OFF OFF OFF CLOSED CLOSED

7. Automatic

Shut-off

water inlet valve energizes for 7 seconds. Firmware 2.58 without thermistor - At 3.75 minutes the water pump de-energizes for 25 seconds. When the

pump restarts the water inlet valve energizes for 7 seconds.

Firmware prior to 2.58 - The water fill valve is de-energized by the control board 1 minute after the freeze cycle starts - The control board will energize

* Condenser Fan Motor: The fan motor is wired through a fan cycle pressure control; therefore, it may cycle on and off.

** Firmware 2.58 with thermistor - when the water temperature reaches 34°F the water pump de-energizes for 25 seconds . When the pump restarts the

the water inlet valve for 7 seconds one last time, 3 minutes into the freeze cycle, regardless of float position.

*** Will be energized during harvest when time exceeds 3.5 minutes.

Part Number STH042 4/16 53

**** The water pump de-energizes for 25 seconds then re-energizes

Operational Checks

ICE THICKNESS CHECK

After a harvest cycle, inspect the ice cubes in the ice
storage bin. The ice bridge connects the ice cubes and
must be set to maintain an ice bridge thickness of 1/8"
(3.2 mm). To adjust the thickness of the bridge refer to ice
thickness adjustment.

ICE THICKNESS ADJUSTMENT

The ice thickness can be adjusted to three levels.

1. Pull forward on the bottom of the bracket until clear
of the tab.

2. Slide the bracket over the desired tab and release.

• The center position is the normal factory setting.

• To increase bridge thickness, raise the water level.

• To decrease bridge thickness, lower the water

level.

THICKER

BRIDGE

54 Part Number STH042 4/16

FACTORY
DEFAULT

THINNER

BRIDGE

MINIMUM/MAXIMUM SLAB WEIGHT

Minimum

Model

U140 1.13 lbs

U190 2.26 lbs

U240 2.26 lbs

U310 2.26 lbs

Ice Weight Per

Cycle lbs

Grams

513 grams

1025 grams

1025 grams

1025 grams

Maximum

Ice Weight Per

Cycle lbs

Grams

1.36 lbs

617 grams

2.93 lbs

1329 grams

2.93 lbs

1329 grams

2.93 lbs

1329 grams

Part Number STH042 4/16 55

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56 Part Number STH042 4/16

Troubleshooting

Problem Checklist

Problem Possible Cause Correction

Ice machine does

not operate

Ice machine

stops, and can

be restarted by

turning the ice

machine OFF/ON.

Ice sheet is thick

Ice machine does

not release ice or is

slow to harvest.

Ice machine does

not release ice or is

slow to harvest.

Ice machine does

not cycle into

harvest mode.

No electrical power to

the ice machine.

Ice machine needs to

be turned on.

Damper in open
position (down).

Safety limit feature

stopping the ice

machine..

Water trough level is

too high.

Power button was

turned off/on during

freeze cycle and
ice remained on

evaporator.

Ice damper was

opened then closed

in the harvest cycle

before the ice released.

Ice machine is dirty. Clean and sanitize the ice

Ice machine is not

level.

Low air temperature

around ice machine
(air-cooled models).

Water regulating valve
leaks in harvest mode

(water-cooled models).

The six-minute freeze

time lock-in has not

expired yet.

Harvest float switch

is dirty.

Harvest float switch

wire is disconnected.

Harvest float switch is

out of adjustment.

Uneven ice fill (thin at

top of evaporator).

Replace the fuse/reset the

breaker/turn on the main

switch/plug power cord

into receptacle.

Press the On/Off button to

start ice making.

Damper must be in upright

position and capable of

swinging freely.

Refer to “Safety Limit

Adjust ice thickness float.

Allow ice to thaw and

release from evaporator,

then restart

Allow ice to thaw and

release from evaporator,

then restart

Level the ice machine

Air temperature must be at

least 40° F (4°C).

Replace water regulating

Wait for freeze lock-in to

Clean and sanitize the ice

Connect the wire

Adjust the harvest float

Refer to “Shallow or

Incomplete Cubes”

Feature”

machine

valve

expire.

machine.

switch.

Part Number STH042 4/16 57

Problem Possible Cause Correction

Ice quality is poor
(soft or not clear).

Ice machine

produces shallow

or incomplete

cubes, or the ice

fill pattern on

the evaporator is

incomplete.

Low ice capacity.

Ice sheet is thick

Poor incoming water

quality.

Water filtration is poor. Replace the filter.

Ice machine is dirty. Clean and sanitize the ice

Water softener is

working improperly (if

applicable).

Ice thickness switch is

out of adjustment.

Water trough level is

too high or too low.

Water filtration is poor. Replace the filter.

Hot incoming water. Connect the ice machine

Incorrect incoming

water pressure.

Ice machine is not

level.

The condenser is dirty. Clean the condenser.

High air temperature

around ice machine
(air-cooled models).

Inadequate clearance

around the ice

machine.

Objects stacked
around ice machine,
blocking condenser

airflow

Hot incoming water. Connect to cold water

Incorrect incoming

water pressure. Water

pressure is too low or

water filter is restricted.

Water trough level is

too high

Power button was

turned off/on during

the freeze cycle and
ice remained on the

evaporator

Ice damper was

opened and closed
in the harvest cycle

before the ice released

Long harvest cycles

with repeated safety

limit indication

Test the quality of the

incoming water and

make appropriate filter

recommendations.

machine.

Repair the water softener

Adjust the ice thickness

Check the water level.

to a cold water supply.

Water pressure must be

20-80 psi (137.9 -551.5 kPa)

Level the ice machine

Air temperature must not

exceed 110° F (43°C).

Provide adequate

clearance

Remove items blocking

Water pressure must be

20-80 psi (137.9 -551.5

kPa). Replace water filter.

Adjust ice thickness float

Allow ice to thaw

and release from the

evaporator, then restart

Allow ice to thaw

and release from the

evaporator, then restart

Clean the ice machine

& perform diagnostic

procedures as required

switch

airflow

58 Part Number STH042 4/16

Control Board Test Mode

NOTE: The ice damper/bin switch can be open or closed
and does not effect the operation of the test mode.

To enter the test mode press and hold the test button on
the control board for 3 seconds. The control board test
mode performs the following functions for a 2 minute
time period:

• Energizes all control board relays

• Energizes all control board lights

• Energizes all touch pad control lights

After 2 minutes the control board will automatically
initiate and complete one ice making cycle, then stop.

Canceling a test cycle:

To cancel a test cycle press the test button a second time.

Restarting a test cycle:

The test cycle will restart each time the test button is
pressed for a 3 second time period.

OPERATING ICE MACHINE WITH BIN AND TOUCH
PAD REMOVED

The ice machine is designed to allow diagnostic
procedures to be performed with the bin removed. The
touch pad is attached to the bin and is disconnected
during the removal process. Use the control board test
mode to operate the ice machine without connecting the
touch pad.

Part Number STH042 4/16 59

Diagnosing an Ice Machine that Will Not Run

Warning

n

High (line) voltage is applied to the control board
at all times. Removing the control board fuse or
pressing the power button will not remove the power
supplied to the control board.

1. Verify primary voltage is supplied to ice machine and
the fuse/circuit breaker is closed.

2. Verify control board fuse is okay.

NOTE: If any control board lights are on, the fuse is okay.

3. Verify the bin switch functions properly. A defective
bin switch can falsely indicate a full bin of ice.

4. Verify power button functions properly. A defective
power button may keep the ice machine in the OFF
mode. Refer to page 98 touch pad diagnostics when
Steps 1 –3 test good.

5. Be sure Steps 1 – 4 were followed thoroughly.
Intermittent problems are not usually related to the
control board. Replace control board if touch pad
operation is correct.

60 Part Number STH042 4/16

Ice Machine Does Not Cycle Into Harvest
when Water Loses Contact with the Harvest
Float Switch

NOTE: The ice machine will make a thick or double
slab when a new freeze cycle is started with ice already
present on the evaporator.

Two of the most common scenarios are:

• Power is cycled off/on with ice on the evaporator.

• The ice damper/bin switch is opened/closed in the

harvest cycle before the ice releases.

Remove all ice from the evaporator before starting
diagnostic procedures.

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.
After six minutes a harvest cycle can be initiated. To allow
the service technician to initiate a harvest cycle without
delay, this feature is not used on the first cycle after
pressing the power button OFF and back to ON.

Step 1 Disconnect power to the ice machine, remove
the electrical panel to allow viewing of the control board
lights and pull the wire connector for the harvest float
switch through the bulkhead and disconnect. Attach
a jumper wire to the wire terminals connected to the
control board.

Step 2 Bypass the freeze time lock-in feature by
pressing the power button to cycle the ice machine on.
Wait until water flows over the evaporator, then refer to
chart.

Result Correction

10 seconds into the freeze cycle
the ice machine cycles from freeze
to harvest and the control board
harvest light energizes.
The harvest light stays off and the
ice machine remains in freeze.

Refer to Float Switch
Diagnostics.

Proceed to Step 3

Part Number STH042 4/16 61

Step 3 Disconnect the harvest float switch wire from
the control board and place a jumper on the control
board harvest float switch terminals. Bypass the freeze
time lock-in feature by pressing the power button to
cycle the ice machine off/on. Wait until water flows over
the evaporator, then refer to chart.

Result Correction

10 seconds into the freeze cycle
the ice machine cycles from freeze
to harvest and the control board
harvest light energizes.
The harvest light comes on, but the
ice machine remains in the freeze
cycle.
The harvest light stays off and the
ice machine remains in freeze.

The ice thickness float
switch wire is causing the
malfunction.

The ice machine is in a 6
minute freeze lock - Cycle
on/off and retest.
Replace the control
board.

62 Part Number STH042 4/16

Ice Machine Cycles Into Harvest Before
Water Loses Contact with the Harvest Float
Switch

Step 1 Disconnect power to the ice machine, remove

the electrical panel to allow viewing of the control board
lights and pull the wire connector for the harvest float
switch through the bulkhead and disconnect.

WIRE CONNECTORS ARE LOCATED BEHIND BULKHEAD

PULL THROUGH GROMMET TO DISCONNECT

HARVEST FLOAT

SWITCH & BRACKET

Part Number STH042 4/16 63

ICE THICKNESS FLOAT

SWITCH & BRACKET

Step 2 Reapply power and press the power button to

cycle the ice machine off/on and bypass the freeze time
lock-in feature. Wait until water flows over the evaporator,
then refer to chart.

Result Correction

The harvest light does not come on
and the ice machine stays in freeze.
The harvest light comes on but the
ice machine stays in a freeze cycle.

10 seconds into the freeze cycle
the ice machine cycles from freeze
to harvest and the control board
harvest light energizes.

Refer to Float Switch
Diagnostics
The ice machine is in a 6
minute freeze lock - Cycle
on/off and retest.
Proceed to Step 3.

Step 3 Disconnect the harvest float switch wire
from the control board and bypass the freeze time
lock-in feature by pressing the power button to cycle
the ice machine off/on. Wait until water flows over the
evaporator, then refer to chart.

Result Correction

The harvest light does not come on. The harvest float switch

wire is causing the

malfunction.
The harvest light comes on but
the ice machine stays in the freeze
sequence.
10 seconds into the freeze cycle
the ice machine cycles from freeze
to harvest and the control board
harvest light energizes.

The ice machine is in a 6

minute freeze lock - Cycle

on/off and retest.

Replace the control

board.

64 Part Number STH042 4/16

Ice Production Check

The amount of ice a machine produces directly relates to
the operating water and air temperatures. This means an
ice machine with a 70°F (21°C) ambient temperature and
50°F (10°C) water produces more ice than the same ice
machine with 90°F (32°C) ambient and 70°F (21°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 (starting on page 121). Use the operating
conditions determined in Step 1 to find published
24-Hour Ice Production:_____

• 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.)

3. Perform an ice production check using the formula
below.

1. + =
Freeze

Time

Harvest

Time

Total Cycle

Time

2. 1440 ÷ =

Minutes

in 24 Hrs.

3. x =

Weight

of One

Harvest

Part Number STH042 4/16 65

Total Cycle

Time

Cycles per

Day

Cycles per

Day

Actual

24-Hour

Production

Weighing the ice is the only 100% accurate check.

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 larger ice machine 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.

66 Part Number STH042 4/16

Installation/Visual Inspection Checklist

Ice machine is not level

• Level the ice machine

Condenser is dirty

• Clean the condenser

Water filtration is plugged (if used)

• Install a new water filter

Water drains are not run separately and/or are not
vented

• Run and vent drains according to the Installation

Manual

Part Number STH042 4/16 67

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.

Water area (evaporator) is dirty

• Clean as needed

Water inlet pressure not between 20 and 80 psig
(1–5bar, 138–552 kPa)

• Install a water regulator valve or increase the water
pressure

Incoming water temperature is not between 40°F (3°C)
and 90°F (32°C)

• If too hot, check the hot water line check valves in
other store equipment

Water filtration is plugged (if used)

• Install a new water filter

Vent tube is not installed on water outlet drain

• See Installation Instructions

Hoses, fittings, etc., are leaking water

• Repair/replace as needed

Water valve is stuck open, closed or is leaking

• Clean/replace as needed

Water is spraying out of the sump trough area

• Stop the water spray

Uneven water flow across the evaporator

• Clean the ice machine

Water is freezing behind the evaporator

• Correct the water flow

Plastic extrusions and gaskets are not secured to the
evaporator

• Remount/replace as needed

68 Part Number STH042 4/16

Ice Formation Pattern

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.

OUTLET

OUTLET

INLET

U0140 U0190 U0240 U0310

INLET

Examples of Evaporator Tubing Routing

Normal Ice Formation

Ice forms across the entire evaporator surface.

At the beginning of the Freeze cycle, it may appear that
more ice is forming on the inlet of the evaporator than at
the outlet. At the end of the Freeze cycle, ice formation
at the outlet will be close to, or just a bit thinner than, ice
formation at the inlet. The dimples in the cubes at the
outlet of the evaporator may be more pronounced than
those at the inlet. This is normal.

If ice forms uniformly across the evaporator surface, but
does not do so in the proper amount of time, this is still
considered a normal ice fill pattern.

Part Number STH042 4/16 69

Extremely Thin at Evaporator Outlet

There is no ice, or a considerable lack of ice formation on
the outlet of the evaporator.

Examples: No ice at all at the outlet of the evaporator, but
ice forms at the inlet half of the evaporator. Or, the ice at
the outlet of the evaporator reaches the correct thickness,
but the outlet of the evaporator already has 1/2" to 1" of
ice formation.

Possible cause: Water loss, low on refrigerant, starving
TXV, hot water supply, faulty float valve, etc.

Extremely Thin at Evaporator Inlet

There is no ice, or a considerable lack of ice formation at
the inlet of the evaporator. Examples: The ice at the outlet
of the evaporator reaches the correct thickness, but there
is no ice formation at all at the inlet of the evaporator.

Possible cause: Insufficient water flow, flooding TXV, etc.

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
backside of the evaporator.

No Ice Formation

The ice machine operates for an extended period, but
there is no ice formation at all on the evaporator.

Possible cause: Water float valve, water pump, starving
expansion valve, low refrigerant charge, compressor, etc.

70 Part Number STH042 4/16

Safety Limit Feature

In addition to the standard safety controls, your
Manitowoc ice machine features built-in safety limits that
will stop the ice machine if conditions arise which could
cause a major component failure.

Service Light: The Service light energizes whenever a
safety limit has been exceeded.

Safety Limit 1

If the freeze time reaches 45 minutes, the control board
automatically initiates a harvest cycle.

• After 3 consecutive 45minute cycles, control board
light SL#1 along with the touch pad service (wrench)
light will flash on/off at 1 second intervals.

• If 6 consecutive 45-minute freeze cycles occur, the
ice machine stops and the SL#1 light on the control
board and the Service (wrench) light on the touch
pad will be on continuously.

Safety Limit 2

• If the harvest time reaches 3.5 minutes, the control
board automatically energizes the water pump and
extends the harvest cycle another 3.5 minutes (7
minutes total).

• If the ice damper does not open and close within the
7 minute harvest cycle the ice machine enters a water
thaw cycle for 170 seconds.

• If the damper does not open/close within the 170
second thaw cycle, a second thaw cycle starts.

• The control board automatically initiates a freeze
sequence when the thaw cycle(s) is complete.

• If 3 consecutive 7 minute harvest/thaw cycles occur,
the ice machine stops and the SL#2 light on the
control board and the Service (wrench) light on the
touch pad will be on continuously.

Part Number STH042 4/16 71

Safety Limit 3

If the freeze time reaches 4 minutes and water is not
sensed (float remains down for 10 continuous seconds)
the ice machine stops.

• Safety Limit 3 is bypassed on the initial cycle (manual
start or after a full bin/safety limit condition). For
all subsequent cycles if the freeze time reaches 4
minutes and water is not sensed, the ice machine
stops and initiates a 30 minute delay period. Control
board lights SL#1 and SL#2 along with the touch pad
Service (wrench) light will flash on/off at 1 second
intervals.

• The ice machine automatically restarts at the end of
the 30 minute delay period and stops flashing the
control board and Service (wrench) lights.

• If 100 consecutive failures occur the ice machine
stops and the touch pad Service (wrench) light
remains energized.

72 Part Number STH042 4/16

Determining Which Safety Limit Stopped the Ice
Machine:

When a safety limit condition causes the ice machine
to stop, the safety limit light on the control board
continually flashes on and off.

CONTROL BOARD SAFETY LIMIT LIGHT OPERATION,
BEFORE THE POWER BUTTON HAS BEEN CYCLED ON/OFF:

Watch the safety limit lights on the control board:

• SL#1 flashes = 3 or more 45 minute cycles

• SL#1 continuously on = Six 45minute freeze cycles

• SL#2 flashes = One 3.5 minute harvest cycles

• SL#2 continuously on = 3 consecutive 3.5 minute
harvest cycles

• SL#1 & SL#2 flash = SL#3, neither float opened within
4 minutes of the freeze cycle.

CONTROL BOARD SAFETY LIMIT LIGHT OPERATION
USING THE POWER BUTTON:

1. Press the power button once.

2. Press the power button again to start ice making.

3. Watch the safety limit lights.

• One will flash corresponding to safety limits 1
or2.

4. Safety limit 3 is indicated by both SL#1 & SL#2
flashing.

After safety limit indication, the ice machine will restart
and run until a safety limit is exceeded again.

Safety Limit Notes

• 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 power button is cycled OFF and then ON prior
to reaching the 100-harvest point, the last safety limit
exceeded will be indicated.

Part Number STH042 4/16 73

Safety Limit Checklist

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.

Safety Limit #1

Freeze time exceeds 45 minutes for 3 consecutive
freeze cycles.

Possible Cause Checklist

Improper installation

• Refer to “Installation/Visual Inspection Checklist” on
page 67

Water System

• Water Level too high or defective float switch (water
escaping water trough)

• Low water pressure (20 psig min.)

• High water pressure (80 psig max.)

• High water temperature (90°F/32.2°C max.)

• Clogged water distribution tube

• Dirty/defective water inlet valve

• Defective water pump

Electrical System

• Harvest cycle not initiated electrically

• Contactor not energizing

• Compressor electrically non-operational

• Restricted condenser air flow

• High inlet air temperature (110°F/43.3°C max.)

• Condenser discharge air re-circulation

• Dirty condenser fins

• Defective fan cycling control

• Defective fan motor

• Low water pressure (20 psig min.)

• High water temperature (90°F/32.2°C max.)

• Dirty condenser

74 Part Number STH042 4/16

Refrigeration System

• Non-Manitowoc components

• Improper refrigerant charge

• Defective compressor

• TXV starving or flooding (check bulb mounting)

• Non-condensible in refrigeration system

• Plugged or restricted high side refrigerant lines or
component

• Defective harvest valve

Part Number STH042 4/16 75

Safety Limit #2

Harvest time exceeds 3.5 minutes for 3 Consecutive
harvest cycles.

Possible Cause Checklist

Improper installation

• Refer to “Installation/Visual Inspection Checklist” on
page 67

Water System

• Water area (evaporator) dirty

• Dirty/defective water dump valve

• Vent tube not installed on water outlet drain

• Water freezing behind evaporator

• Plastic extrusions and gaskets not securely mounted
to the evaporator

• Low water pressure (20 psig min.)

• Loss of water from sump area

• Clogged water distribution tube

• Dirty/defective water inlet valve

• Defective water pump

Electrical system

• Water inlet valve defective

• Bin switch defective

• Premature harvest

Refrigeration system

• Non-Manitowoc components

• Improper refrigerant charge

• Defective harvest valve

• TXV flooding (check bulb mounting)

• Defective fan cycling control

76 Part Number STH042 4/16

Safety Limit 3

Freeze time reaches 4 minutes and water is not
sensed.

Possible Cause Checklist

Improper installation

• Refer to “Installation/Visual Inspection Checklist” on
page 67

Water System

• Dirty/defective water dump valve

• Low water float valve dirty or defective

• Vent tube not installed on water outlet drain

• Low water pressure (20 psig min.)

• Dirty defective water filter (when used)

• Loss of water from sump area

• Dirty/defective water inlet valve

Electrical system

• Water inlet valve coil defective

• Low water float valve defective

Part Number STH042 4/16 77

Analyzing Discharge Pressure

1. Determine the ice machine operating conditions:

Air temp. entering condenser ______

Air temp. around ice machine ______

Water temp. entering sump trough ______

2. Refer to “Cycle Times, 24 Hr. Ice Production and
Refrigerant Pressure Charts” on page 127 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. It is normal for the
discharge pressure to be higher at the beginning of the
freeze cycle (when load is greatest), then drop through
out the freeze cycle.

Harvest Cycle

PSIG

78 Part Number STH042 4/16

Discharge Pressure High Checklist

Improper Installation

• Refer to “Installation/Visual Inspection Checklist” on

page 67

Restricted Condenser Air Flow

• High inlet air temperature

• Condenser discharge air re-circulation

• Dirty condenser fins

• Defective fan cycling control

• Defective fan motor

Improper Refrigerant Charge

• Overcharged

• Non-condensable in system

• Wrong type of refrigerant

Other

• Non-Manitowoc components in system

• High side refrigerant lines/component restricted

(before mid-condenser)

Freeze Cycle Discharge Pressure Low Checklist

Improper Installation

• Refer to “Installation/Visual Inspection Checklist” on

page 67

Improper Refrigerant Charge

• Undercharged

• Wrong type of refrigerant

Other

• Non-Manitowoc components in system

• High side refrigerant lines/component restricted

(before mid-condenser)

• Defective fan cycle control

NOTE: Do not limit your diagnosis to only the items listed
in the checklists.

Part Number STH042 4/16 79

Analyzing Suction Pressure

The suction pressure gradually drops throughout the
freeze cycle. The actual suction pressure (and drop rate)
changes as the air and water temperature entering the
ice machine changes. These variables also determine the
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.

NOTE: Analyze discharge pressure before analyzing
suction pressure. High or low discharge pressure may be
causing high or low suction pressure.

80 Part Number STH042 4/16

Procedure

Step

1. Determine the ice machine operating conditions.

Example:
Air temp. entering condenser: 90°F/32.2°C
Air temp. around ice machine: 80°F/26.7°C
Water temp. entering water fill valve: 70°F/21.1°C

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.

Example:
Published freeze cycle time: 14.8 - 15.9 minutes
Published freeze cycle suction pressure: 65 - 26 psig

2B. Compare the published freeze cycle time and published
freeze cycle suction pressure. Develop a chart.

Example:
Published Freeze Cycle Time (minutes)

1 2 4 7 10 12 14
| | | | | | |
65 55 47 39 34 30 26

Published Freeze Cycle Suction Pressure (psig)
In the example, the proper suction pressure should be
approximately 39 psig at 7 minutes; 30 psig at 12 minutes; etc.

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.

Example:
Manifold gauges were connected to the example ice machine
and suction pressure readings taken as follows: ________ PSIG
Beginning of freeze cycle: 79 (at 1 min.)
Middle of freeze cycle: 48 (at 7 min.)
End of freeze cycle: 40 (at 14 min.)

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.

Example:
In this example, the suction pressure is considered high
throughout the freeze cycle. It should have been:
Approximately 65 psig (at 1 minute) – not 79
Approximately 39 psig (at 7 minutes) – not 48
Approximately 26 psig (at 14 minutes) – not 40

Part Number STH042 4/16 81

Suction Pressure High Checklist

Improper Installation

• Refer to “Installation/Visual Inspection Checklist” on
page 67

Discharge Pressure

• Discharge pressure is too high, and is affecting
suction pressure, refer to “Discharge Pressure High
Checklist” on page 79.

Improper Refrigerant Charge

• Overcharged

• Wrong type of refrigerant

• Non-condensable in system

Other

• Non-Manitowoc components in system

• Harvest valve leaking

• TXV flooding (check bulb mounting)

• Defective compressor

82 Part Number STH042 4/16

Suction Pressure Low Checklist

Improper Installation

• Refer to “Installation/Visual Inspection Checklist” on
page 67

Discharge Pressure

• Discharge pressure is too low, and is affecting suction
pressure, refer to “Freeze Cycle Discharge Pressure
Low Checklist” on page 79.

Improper Refrigerant Charge

• Undercharged

• Wrong type of refrigerant

Other

• Non-Manitowoc components in system

• Improper water supply over evaporator refer to
”Water System Checklist” on page 68.

• 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.

Part Number STH042 4/16 83

Harvest Valve

General

The harvest valve is an electrically operated valve that
opens when energized, and closes when de-energized.

Normal Operation

The valve is de-energized (closed) during the freeze cycle
and energized (open) during the harvest cycle. The valve
is positioned between the receiver and the evaporator
and performs two functions:

1. Prevents refrigerant from entering the evaporator
during the freeze cycle.

The harvest valve is not used during the freeze
cycle. The harvest valve is de-energized (closed)
preventing refrigerant flow from the receiver into
the evaporator.

2. Allows refrigerant vapor to enter the evaporator in
the harvest cycle.

During the harvest cycle, the harvest valve is
energized (open) allowing refrigerant gas from the
discharge line of the compressor to flow into the
evaporator. The heat is absorbed by the evaporator
and allows release of the ice slab.

Exact pressures vary according to ambient temperature
and ice machine model. Harvest pressures can be found
in the Cycle Time/24 Hour Ice Production/ Refrigerant
Pressure Charts in this book.

84 Part Number STH042 4/16

Harvest Valve Analysis

The valve can fail in two positions:

• Valve will not open in the harvest cycle.

• Valve remains open during the freeze cycle.

VALVE WILL NOT OPEN IN THE HARVEST CYCLE

Although the circuit board has initiated a harvest cycle,
the evaporator temperature remains unchanged from the
freeze cycle.

VALVE REMAINS OPEN IN THE FREEZE CYCLE:

Symptoms of a harvest valve remaining partially open
during the freeze cycle can be similar to symptoms of
an expansion valve, float valve or compressor problem.
Symptoms are dependent on the amount of leakage in
the freeze cycle.

A small amount of leakage will cause increased freeze
times and an ice fill pattern that is “Thin at the Outlet”, but
fills in at the end of the cycle.

As the amount of leakage increases the length of the
freeze cycle increases and the amount of ice at the outlet
of the evaporator decreases.

Refer to the Parts Manual for proper valve application. If
replacement is necessary, use only “original” Manitowoc
replacement parts.

Part Number STH042 4/16 85

Use the following procedure and table to help determine
if a harvest valve is remaining partially open during the
freeze cycle.

1. Wait five minutes into the freeze cycle.

2. Feel the inlet of the harvest valve(s).

Important

Feeling the harvest valve outlet or across the harvest
valve itself will not work for this comparison.

The harvest valve outlet is on the suction side (cool
refrigerant). It may be cool enough to touch even if
the valve is leaking.

3. Feel the compressor discharge line.

Warning

n

The inlet of the harvest 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 harvest
valves to the temperature of the compressor
discharge line.

86 Part Number STH042 4/16

Findings Comments

The inlet of the harvest
valve is cool enough to

touch and the compressor

discharge line is hot.

Cool & Hot

The inlet of the harvest

valve is hot and approaches

the temperature of a hot

compressor discharge line.

Hot & Hot

Both the inlet of the harvest

valve and the compressor

discharge line are cool

enough to touch.

Cool & Cool

This is normal as the discharge

line should always be too hot to
touch and the harvest valve inlet,
although too hot to touch during

harvest, should be cool enough

to touch after 5 minutes into the

This is an indication something is

wrong, as the harvest valve inlet

did not cool down during the

freeze cycle. If the compressor

dome is also entirely hot, the
problem is not a harvest valve
leaking, but rather something

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

harvest valve leaking.

5. Record your findings on the table.

freeze cycle.

Part Number STH042 4/16 87

Comparing Evaporator Inlet/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°F (4°C) 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.

___________ ___________ ___________

Inlet

Temperature

Difference must be within
7°F (4°C) at 5minutes into

the freeze cycle

Outlet

Temperature

5. Use this with other information gathered on the
Refrigeration System Operational Analysis Table to
determine the ice machine malfunction.

88 Part Number STH042 4/16

Discharge Line Temperature Analysis

GENERAL

Knowing if the discharge line temperature is
increasing, decreasing or remaining constant can be
an important diagnostic tool. Maximum compressor
discharge line temperature on a normally operating
ice machine steadily increases throughout the freeze
cycle. Comparing the temperatures over several cycles
will result in a consistent maximum discharge line
temperature.

Ambient air temperatures affect the maximum discharge
line temperature.

Higher ambient air temperatures at the condenser =
higher discharge line temperatures at the compressor.

Lower ambient air temperatures at the condenser = lower
discharge line temperatures at the compressor.

Regardless of ambient temperature, the freeze cycle
discharge line temperature will be higher than 150°F
(66°C) on a normally operating ice machine.

PROCEDURE

Connect a temperature probe on the compressor
discharge line within 6" (15.2 cm) of the compressor.
Observe the discharge line temperature for the last three
minutes of the freeze cycle and record the maximum
discharge line temperature.

Part Number STH042 4/16 89

Discharge Line Temperature Above 150°F (66°C) at
End of Freeze Cycle:

Ice machines that are operating normally will have
consistent maximum discharge line temperatures above
150°F (66°C).

Verify the expansion valve sensing bulb is positioned and
secured correctly.

Discharge Line Temperature Below 150°F (66°C) at
End of Freeze Cycle

Ice machines that have a flooding expansion valve
will have a maximum discharge line temperature that
decreases each cycle.

Verify the expansion valve sensing bulb is 100% insulated
and sealed airtight. Condenser air contacting an
incorrectly insulated sensing bulb will cause overfeeding
of the expansion valve.

90 Part Number STH042 4/16

Refrigeration Component Diagnostics

All electrical and water related problems must be
corrected before these charts will work properly. These
tables must be used with charts, checklists and other
references to eliminate refrigeration components not
listed and external items and problems that will cause
good refrigeration components to appear defective.

The tables list four 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.

Part Number STH042 4/16 91

Procedure

Step 1 Complete each item individually in the

“Operational Analysis” column.

Enter check marks () in the 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.

Perform the procedures and check all information listed.
Each item in this column has supporting reference
material.

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 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.

92 Part Number STH042 4/16

Final Analysis

The column with the highest number of check marks
identifies the refrigeration problem.

Column 1 – Harvest Valve Leaking

A leaking harvest valve must be replaced.

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.

Add refrigerant charge in 2 oz. increments as a diagnostic
procedure to verify a low charge. (Do not add more
than the total charge of refrigerant). 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, evacuate the system and weigh in the proper
charge.

If the problem is not corrected by adding charge, the
expansion valve is faulty.

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.

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.

Part Number STH042 4/16 93

10% of charted capacity.

before proceeding with chart.

Calculated (actual) 24 hour ice production_______________

NOTE: The ice machine is operating properly if the ice fill pattern is normal and ice production is within

Ice Production Published 24 hour ice production________________

Operational Analysis 1 2 3 4

All installation and water related problems must be corrected

System

Installation and Water

Refrigeration Component Diagnostic Chart

94 Part Number STH042 4/16

Ice formation is normal

-or-

entire evaporator

No ice formation on

1

Stops on safety limit:

-or-

Ice formation is normal

Ice formation is

extremely thin on outlet

extremely thin on outlet

Operational Analysis 1 2 3 4

Ice Formation Pattern Ice formation is

-or-

Ice formation is

of evaporator

of evaporator

No ice formation on

extremely thin on the

bottom of evaporator

-or-

entire evaporator

No ice formation on

-or-

entire evaporator

No ice formation on

evaporator

1 or 2

Stops on safety limit:

1

Stops on safety limit:

1 or 2

Stops on safety limit:

Safety Limits

Refer to “Analyzing Safety

Limits” to eliminate all non-

refrigeration problems.

Part Number STH042 4/16 95

High

Suction pressure is

High

Suction pressure is

Low

Suction pressure is

eliminate problems and/or components not listed on this table before proceeding.

checklist to eliminate problems and/or components not listed on this table before proceeding.

If discharge pressure is High or Low, refer to freeze cycle high or low discharge pressure problem

If suction pressure is High or Low refer to freeze cycle high or low suction pressure problem checklist to

Freeze Cycle

Operational Analysis 1 2 3 4

96 Part Number STH042 4/16

DischargePressure

________ ______ ______

Freeze Cycle

SuctionPressure

1 minute Middle End

High

Suction pressure is

________ ______ ______

1 minute Middle End

and

and

The compressor

discharge line is

The compressor

discharge line is

HOT

COOL

Discharge line temp

Discharge line temp

150°F (66°C) or higher

at the end of freeze cycle

TXV Flooding Compressor

less than 150°F (66°C)

at the end of freeze cycle

COOL

inlet is

The harvest valve

COOL

inlet is

The harvest valve

Low On Charge

Final Analysis

Harvest Valve

-or-

Leaking

Enter total number of boxes

TXV Starving

checked in each column.

and

and

Harvest Valve

The compressor

discharge line is

The compressor

discharge line is

HOT

HOT

Discharge line temp

Discharge line temp

Discharge Line Temp.

150°F (66°C) or higher

150°F (66°C) or higher

Record freeze cycle

at the end of freeze cycle

at the end of freeze cycle

end of freeze cycle.

discharge line temp at the

COOL

inlet is

The harvest valve

HOT

inlet is

The harvest valve

Operational Analysis 1 2 3 4

Part Number STH042 4/16 97

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98 Part Number STH042 4/16

Component Check Procedures

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, 10 amp.

Warning

n

High (line) voltage is applied to the control board
at all times. Removing the control board fuse or
pressing the power button will not remove the power
supplied to the control board.

Check Procedure

1. If the curtain light is on with the ice damper closed,
the fuse is good.

Warning

n

Disconnect electrical power to the entire ice machine
before proceeding.

2. Remove the fuse. Check the resistance across the
fuse with an ohmmeter.

Reading Result

Open (OL) Replace fuse
Closed (O) Fuse is good

Part Number STH042 4/16 99

Bin Switch

Function

Bin switch operation is controlled by the movement of
the ice damper. The bin switch has two main functions:

1. Terminating the harvest cycle and returning the ice
machine to the freeze cycle.

This occurs when the bin switch is opened and
closed again within 7 seconds of opening during the
harvest cycle.

2. Automatic ice machine shut-off.

If the storage bin is full at the end of a harvest cycle,
the sheet of cubes fails to clear the ice damper and
holds it down. After the ice damper is held down 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 ice damper. As the ice
damper swings back to the operating position, the
bin switch closes and the ice machine restarts.

Important

The ice damper must be up (bin switch closed) to
start ice making.

Check Procedure

1. Press the power button to OFF.

2. Watch the curtain light on the control board.

3. Move the ice damper upward, toward the
evaporator. The bin switch must close. The curtain
light “on” indicates the bin switch has closed
properly.

4. Move the ice damper away from the evaporator. The
bin switch must open. The curtain light “off” indicates
the bin switch has opened properly.

100 Part Number STH042 4/16