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Manitowoc QM20 - User Manual

Manitowoc QM20
236 pages
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Technician’s
Handbook
This manual is updated as new information and models are
released. Visit our website for the latest manual.
www.manitowocice.com
America’s #1 Selling Ice Machine
Manitowoc
QM20/QM30/QM45
SM50
Q130/Q170/Q210/Q270
Undercounter
Ice Machines
Part Number 80-01111-9 7/10

Table of Contents

Questions and Answers

  • M
    Michelle MooreJul 31, 2025
    What to do if my Manitowoc QM20 Ice Maker runs but no ice is produced?
    • D
      Daniel RyanAug 1, 2025
      If your Manitowoc Ice Maker is running but not producing ice, there might be several reasons: * Ensure the ice machine has a water supply. * Verify the incoming water pressure is within the range of 20-80 psi (1.4-5.5 bar). * Check if the spray nozzle is blocked with mineral buildup; if so, clean and sanitize the ice machine. * Confirm the ambient temperature is between 50°F and 110°F (10°C and 43°C). * Refer to thermistor diagnostics.
  • Z
    zblevinsAug 8, 2025
    Why is the freeze cycle long and ice production low on my Manitowoc Ice Maker?
    • M
      Michael RyanAug 8, 2025
      A long freeze cycle and low ice production in your Manitowoc Ice Maker can be due to several factors: * The water temperature might be too high. Connect the machine to a cold water supply and check the check valves in faucets and other equipment. * The condenser might be dirty. Clean the condenser. * The air temperature entering the condenser may be too high. Ensure it does not exceed 120°F (39°C). * The water inlet valve filter screen could be dirty. Remove the water inlet valve and clean the filter screen. * The water inlet valve might be stuck open or leaking. Turn off the ice machine; if water continues to enter, verify water pressure and replace the valve if necessary. * There might be a refrigeration problem. Refer to refrigeration diagnostics.
  • J
    Joshua CooperAug 16, 2025
    How to troubleshoot a Manitowoc QM20 that will not harvest?
    • B
      bakerkellyAug 16, 2025
      If your Manitowoc Ice Maker is not harvesting, here are a few things you can check: * Verify cubes are present in the evaporator and the freeze time exceeds the freeze chart cycle time. * Observe the control board light: a steady light indicates normal thermistor operation. * Reset the ice machine. * Verify the water inlet valve is energized during the entire harvest cycle and water flow is normal. * Check for power at the hot gas valve.
  • C
    Charles MejiaAug 23, 2025
    Why is the ice quality poor in my Manitowoc QM20 Ice Maker?
    • M
      mckinneyreginaAug 23, 2025
      Poor ice quality in your Manitowoc Ice Maker, such as shallow, incomplete, or white cubes, can stem from: * A dirty ice machine. Clean and sanitize it. * Poor water filtration. Replace the filter. * An improperly working water softener (if applicable). Repair the water softener. * Poor incoming water quality. Contact a qualified company to test the water and recommend appropriate filters.

Summary

Safety Notices

Warning: Personal Injury Potential

Alerts to potential personal injury situations; read before proceeding.

Caution: Equipment Damage Potential

Alerts to situations that could damage equipment; read before proceeding.

Important Pre-reading

Caution: Installation and Maintenance Essentials

Emphasizes essential installation, care, and maintenance for equipment.

Warning: Potential Personal Injury

Warns against operating misused, abused, neglected, or altered equipment.

Warning: Refrigerant Handling Safety

Highlights potential personal injury situations when dealing with refrigerant.

General Information

Ice Machine Warranty Information

Details warranty coverage for parts, labor, and specific components.

Installation

Electrical Requirements

Outlines voltage, fuse, and circuit breaker specifications.

Troubleshooting

Diagnosing Machine Not Running

Steps to diagnose why the ice machine fails to start or run.

Safety Limit Feature Overview

Information on built-in safety limits that stop the machine to prevent failure.

Hot Gas Valve Troubleshooting

Diagnostic steps and potential issues related to the hot gas valve.

Evaporator Inlet;Outlet Temperature Comparison

Comparing evaporator temperatures for diagnosing malfunctions.

Component Check Procedures

Main Fuse Function and Testing

Details the function, specifications, and testing of the main fuse.

Bin Switch Function and Testing

Explains the function and provides a check procedure for the bin switch.

Bin Thermostat Information

Provides bin thermostat specifications and checks for various models.

Liquid Line Thermistor Information

Details the function and specifications of the liquid line thermistor.

Diagnosing Start Components: Capacitor and Relay

Troubleshooting procedures for the capacitor and relay.

Ice Thickness Probe Information

Information regarding the ice thickness probe.

Compressor Electrical Diagnostics

Procedures for checking compressor resistance and motor windings.

Fan Cycle Control Information

Details the function and specifications of the fan cycle control.

Component Specifications

Total System Refrigerant Charge

Lists refrigerant charge amounts for various models and types.

Charts and Diagrams

Electronic Control Boards Diagrams

Diagrams illustrating the layout of electronic control boards.

Ice Machine Warranty Details

Owner Warranty Registration Card Instructions

Instructions for completing and mailing the warranty registration card.

Commercial Warranty Coverage

Details warranty coverage for parts and labor in commercial applications.

Warranty Labor Coverage

Warranty Exclusions

Residential Warranty Coverage

Warranty Coverage Details

Warranty Period

Who is Covered by Warranty

Manitowoc Ices Warranty Obligations

Warranty Exclusions and Legal Information

What is Not Covered by Warranty

Implied Warranties and Liability Limitations

Maintenance Procedures

Ice Machine Inspection Checklist

Cleaning the Condenser

Air-Cooled Condenser Cleaning Procedure

Water-Cooled Condenser Cleaning Notes

Interior Cleaning and Sanitizing

Removal of Parts for Cleaning and Sanitizing

Removal from Service and Winterization

General Precautions

Winterization Procedure for Air-Cooled Machines

Winterization Procedure for Water-Cooled Machines

Ice Machine Operation

Initial Start-up Procedures

Freeze Sequence Explanation

Harvest Sequence Explanation

Automatic Shut-off Functionality

Energized Parts Chart

Troubleshooting and Diagnostics

Diagnosing Machine Not Running (QM45;Q130;Q170;Q210;Q270)

Steps to diagnose why the ice machine fails to start or run.

Diagnosing Ice Thickness Control Circuitry

Troubleshooting the ice thickness sensing circuit for proper operation.

Troubleshooting Premature Harvest

Diagnosing cycles into harvest before water contact with the ice thickness probe.

Ice Production Check

Installation and Visual Inspection Checklist

A checklist for initial installation and visual checks of the ice machine.

Water System Troubleshooting Checklist

Checklist for identifying and resolving water-related issues.

Ice Formation Pattern Analysis

Analysis of ice formation patterns for diagnosing machine malfunctions.

Safety Limit Feature Troubleshooting

Information on built-in safety limits that stop the machine.

Understanding Safety Limit Functions

Details on safety limit controls and determining the cause of shutdown.

Analyzing Safety Limit Causes

Explains why safety limits may stop the ice machine.

Safety Limit Condition Checklists

Checklists to assist technicians with safety limit analysis.

Analyzing Discharge Pressure

Procedure for analyzing discharge pressure readings.

Analyzing Suction Pressure

Procedure for analyzing suction pressure readings.

Hot Gas Valve Overview

Evaporator Temperature Comparison

Discharge Line Temperature Analysis

Procedure for analyzing the discharge line temperature.

Refrigeration Component Diagnostic Chart

Chart for diagnosing refrigeration components based on operational analysis.

Diagnostic Chart Procedure

Steps for using the refrigeration component diagnostic chart.

Final Analysis of Diagnostic Results

Interpreting the diagnostic chart results to identify refrigeration problems.

QM20;QM30 Troubleshooting: Machine Not Running

Steps to diagnose why QM20/QM30 ice machines fail to start or run.

QM20 Refrigeration Diagnostics

QM30 Refrigeration Diagnostics

QM20;QM30 Ice Formation Pattern Analysis

QM20;QM30 Ice Production Check

QM45 Electrical Troubleshooting

QM45 Refrigeration Diagnostics

Expansion Valve and Refrigerant Charge Issues

SM50 Troubleshooting: Machine Not Running

Steps to diagnose why SM50 ice machines fail to start or run.

Troubleshooting: Ice Machine Will Not Harvest

Troubleshooting steps when the ice machine fails to harvest ice.

Troubleshooting: Poor Ice Quality

Troubleshooting: Long Freeze Cycle;Low Production

Troubleshooting: Machine Runs, No Ice Produced

Discharge Pressure Analysis Procedure

Discharge Pressure High;Low Checklists

Suction Pressure Analysis Procedure

Suction Pressure High;Low Checklists

Hot Gas Valve Operation

Hot Gas Valve Failure Analysis

Ice Production Check Procedure

Procedure to verify the ice machine's ice production rate.

Adjusting Cube Weight

Component Checks and Specifications

Main Fuse Check Procedure

Bin Switch Function and Check Procedure

Bin Thermostat Function and Specifications (QM20;QM30)

SM50 Bin Thermostat Function and Specifications

Bin Thermostat Adjustment Procedure

Liquid Line Thermistor Function and Specifications

Temperature;Resistance Chart for Thermistors

Diagnosing Start Components: Capacitor

Diagnosing Start Components: Relay

ON;OFF;WASH Toggle Switch Check

Procedure to check the operation of the ON/OFF/WASH toggle switch.

Ice Thickness Probe Functionality

Freeze Time Lock-In Feature Explanation

Maximum Freeze Time Safety Feature

Compressor Electrical Diagnostics: Resistance Values

Procedure for checking compressor resistance (ohm) values.

Compressor Electrical Diagnostics: Motor Windings to Ground

Procedure to check motor windings for continuity to ground.

Compressor Drawing Locked Rotor Diagnosis

Compressor Drawing High Amps Diagnosis

Fan Cycle Control Function and Specifications

Liquid Line Thermistor Specs

Specifications for liquid line thermistors.

Refrigerant Handling and System Maintenance

Refrigerant Recovery and Recharging Procedures

Self-Contained Recovery;Evacuation

Refrigerant Charging Procedures

QM Series Refrigerant Handling Procedures

System Contamination Cleanup Overview

Determining Severity of System Contamination

Contamination and Cleanup Chart

Mild System Contamination Cleanup Procedure

Severe System Contamination Cleanup Procedure

Replacing Controls Without Refrigerant Removal

Component Specifications and Data

Main Fuse Specifications

Bin Switch Information

Bin Thermostat Specifications

ON;OFF;WASH Toggle Switch Specifications

Fan Control Cycle Specifications

High Pressure Cutout (HPCO) Control Specs

Cut-out and cut-in specifications for the HPCO control.

Liquid Line Thermistor Specifications

Total System Refrigerant Charge Information

Performance Charts

Cycle Times, Ice Production, and Pressure Charts

Guidelines used to verify correct ice machine operation and performance.

QM20 Air-Cooled Performance Data

QM30 Air-Cooled Performance Data

QM45 Air-Cooled Performance Data

QM45 Operating Temperatures

SM50 Air-Cooled Performance Data

Q130 Air-Cooled Performance Data (Pre SN 310047287)

Q130 Air-Cooled Performance Data (Post SN 310047287)

Q130 Water-Cooled Performance Data

Q170 Air-Cooled Performance Data

Q210 Air-Cooled Performance Data

Q210 Water-Cooled Performance Data

Q270 Air-Cooled Performance Data

Q270 Water-Cooled Performance Data

Diagrams and Schematics

Wiring Diagrams

Electrical wiring diagrams for various ice machine models.

Wiring Diagram Legend

Explanation of symbols used in wiring diagrams.

QM20 Wiring Diagram

Electrical wiring diagram for the QM20 ice machine.

QM30 Wiring Diagrams (115 V;230 V)

Electrical wiring diagrams for QM30 models at different voltages.

QM45 Wiring Diagram

Electrical wiring diagram for the QM45 ice machine.

SM50 Wiring Diagram

Electrical wiring diagram for the SM50 ice machine.

Q130;Q210 Compressor Wiring Diagrams

Wiring diagrams for Q130/Q210 with different compressor types.

Q130;Q170;Q210 Compressor Wiring Diagrams

Wiring diagrams for Q130/Q170/Q210 with Danfoss compressor.

Q270 Compressor Wiring Diagrams

Wiring diagrams for Q270 with Tecumseh and Danfoss compressors.

Electronic Control Board Diagrams

Tubing Schematics

Diagrams showing the layout of refrigerant tubing within the machines.

Manitowoc QM20 Specifications

General IconGeneral
ModelQM20
Ice TypeCube
Condenser TypeAir-Cooled
Electrical115V, 60Hz, 1.5A
Power Supply115V, 60Hz, 1.5A

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