Manitowoc QM20 User Manual (English)

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.

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.

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.

Model	QM20
Ice Type	Cube
Condenser Type	Air-Cooled
Electrical	115V, 60Hz, 1.5A
Power Supply	115V, 60Hz, 1.5A

Model

QM20

Ice Type

Cube

Condenser Type

Air-Cooled

Electrical

115V, 60Hz, 1.5A

Power Supply

115V, 60Hz, 1.5A

Manitowoc QM20 User Manual

Table of Contents

Questions and Answers:

Manitowoc QM20 Specifications

Summary

Safety Notices

Warning: Personal Injury Potential

Caution: Equipment Damage Potential

Important Pre-reading

Caution: Installation and Maintenance Essentials

Warning: Potential Personal Injury

Warning: Refrigerant Handling Safety

General Information

Ice Machine Warranty Information

Installation

Electrical Requirements

Troubleshooting

Diagnosing Machine Not Running

Safety Limit Feature Overview

Hot Gas Valve Troubleshooting

Evaporator Inlet/Outlet Temperature Comparison

Component Check Procedures

Main Fuse Function and Testing

Bin Switch Function and Testing

Bin Thermostat Information

Liquid Line Thermistor Information

Diagnosing Start Components: Capacitor and Relay

Ice Thickness Probe Information

Compressor Electrical Diagnostics

Fan Cycle Control Information

Component Specifications

Total System Refrigerant Charge

Charts and Diagrams

Electronic Control Boards Diagrams

Ice Machine Warranty Details

Owner Warranty Registration Card Instructions

Commercial Warranty Coverage

Warranty Labor Coverage

Warranty Exclusions

Residential Warranty Coverage

Warranty Coverage Details

Warranty Period

Who is Covered by Warranty

Manitowoc Ice's 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)

Diagnosing Ice Thickness Control Circuitry

Troubleshooting Premature Harvest

Ice Production Check

Installation and Visual Inspection Checklist

Water System Troubleshooting Checklist

Ice Formation Pattern Analysis

Safety Limit Feature Troubleshooting

Understanding Safety Limit Functions

Analyzing Safety Limit Causes

Safety Limit Condition Checklists

Analyzing Discharge Pressure

Analyzing Suction Pressure

Hot Gas Valve Overview

Evaporator Temperature Comparison