Manitowoc Ice Machine How to and Troubleshooting Guide
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Manitowoc Ice Machine How to and Troubleshooting Guide

An ice machine is a crucial kitchen gadget if beverages are the main part of your menu. As such an optimally performing ice machine is key to your success. Keep reading to learn how to maintain and troubleshoot your Manitowoc ice machine for optimal performance all year round.

Manitowoc Ice Machine Not Making Ice

Follow the steps below to troubleshoot the ice maker.

If the Manitowoc ice maker does not power on or operate when the power switch is set to “ICE.”;

  • Make sure that the power switch is fully on “ICE” and not “OFF” or “CLEAN.”
  • If the machine does not turn on, check that the power cord is connected to a working power outlet.
  • If the power outlet is controlled by a wall switch, check that the switch is in the “On” position.
  • If you are unsure whether the power outlet is working, plug another device into the outlet and check for power.
  • If you are unable to work another device on the outlet, the ice machine may have blown a fuse or tripped a circuit breaker.
  • Replace the fuse or reset the breaker as needed.

Faulty compressor

Another reason the ice maker is not working is a faulty compressor. The Manitowoc ice maker will not make ice if the compressor does not start.

If the compressor will not start, even if the gear motor is running;

  • Check for water in the water reservoir.
  • Make sure the water valve is open and that the float valve screen isn’t clogged.
    • When clogged, the screen will reduce the flow of water. In order for the compressor to start, water needs to touch the water sensor. Clean the screen as needed.
  • Check for a broken fuse or tripped circuit breaker and change the fuse or reset the breaker as needed.
    • Another potential reason the compressor to not start is the condensing unit is not receiving power.

Why Does My Manitowoc Ice Machine Keep Shutting Off?

  1. The Safety Limit is active

When your Manitowoc ice machine shuts down prematurely, it most likely is going off on what’s called a safety limit.  On Q Series ice machines there are 2 different safety limits, that will help you diagnose the problem. 

To check which safety limit is the problem, simply turn your machine from the off position to ice and count how many times the harvest light flashes. 

Below are what the 2 safety limits mean;

Safety Limit #1

If the freeze time reaches 60 minutes, the control board automatically initiates a harvest cycle.  If 3 consecutive 60-minute freeze cycles occur, the ice machine stops.

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Safety Limit #2

If the harvest time reaches 3.5 minutes, the control board automatically returns the ice machine to the freeze cycle.  If three consecutive 3.5-minute harvest cycles occur, the ice machine stops.

Note: Safety Limit #2 is a more common safety limit and can be caused by the ice maker simply being dirty.

2. Dirty Evaporator

A dirty evaporator will hold ice and not allow it to fall until it is mostly melted away.  Because there is not enough ice to force the water curtain open and break the bin switch, the machine simply thinks it never harvested.

3. Malfunctioning Bin switch

 Another culprit, which can also lead to intermittent problems, is a failed bin switch. A missing magnet on the water curtain or your water curtain being broken will cause your bin switch to fail. The magnetic bin switch on a Manitowoc ice machine relies on proximity to the magnet to know when to terminate the harvest cycle.  This switch will not read if it does not make proper contact with the magnet.  To remedy this issue simply replace the water curtain.

The only way to properly test a magnetic bin switch is to OHM it out and look for consistency.  However, it is possible for the switch to fail on say the 100th time, so if you are experiencing regular Safety Limit #2 lockouts, it might be a good idea to go ahead and eliminate the bin switch by replacing it.

How Do You Reset A Manitowoc Ice Machine?

Below are some procedures you can follow when resetting different Manitowoc ice machine models;

Rebooting NEO Undercounter Machines

One of our top members, fix bear, shared the reset procedure for NEO under counter ice machines in an older discussion post. Below is a quick summary of the rebooting process:

  • Press the OFF button for 3 seconds.
  • Wait for ice to melt off the evaporator.
  • Disconnect power to the machine and wait about 10 seconds.
  • Plug the machine back in and press the ON button.
  • A blue light should appear, indicating that the unit has been reset.

Resetting the Control Board on NEO Undercounter Machines

The Manitowoc NEO Technician Handbook says that if switches aren’t working properly on the NEO touchpad, a reset and test will need to be performed. Disconnect power to the ice machine to reset the control board. Restore power to the machine about 10 seconds later and test out the switches again. If they still don’t work, run an Ohm test to see if the issue isn’t associated with the control board or wiring.

Resetting Safety Limits on NEO Undercounter Machines

Safety limits are designed to shut down the machine when issues are present that could damage the unit. One safety limit is designed to shut down the machine if there is a long harvest. And the other is designed to shut down the machine if there is a long freeze cycle.

pressing the ON/OFF button and starting a new ice-making cycle will reset the safety limits.

Resetting Factory Defaults on Indigo Machines

  • Press the menu key to access the menu.
  • Press the down arrow key to scroll to “Fact Default.” Press the right arrow key to select.
  • Press the checkmark key to confirm and activate the change.
  • Factory default will activate and turn off all previously set reminders.

How Do I Turn Off a Manitowoc Ice Maker?

Simply unplugging the ice machine is the best way to turn it off. If you cannot unplug the ice machine, the next best course of action is to locate the breaker that your ice machine is on and turn it to “off”

If either of these options is not possible, please follow the steps below;

  • Open the front panel of your ice machine by unscrewing the (1) top and (1) bottom screw of the Manitowoc front panel with a Phillips-head screwdriver.
  • The door will swing open.
  • Make sure you do not lose the screws as they are necessary to secure the front panel.
  • On the top of the display panel, there will be three buttons.
  • On the far left is the power button.
  • Push and hold the power button until the unit powers off.
  • Once unit has powered off, the screen will go blank.
  • Please close the front door of the machine, and replace the 2 screws, thoroughly securing the front panel.

How Do You Turn Your Manitowoc Ice Machine Back On?

To turn the ice machine on, either plug the unit back into the outlet or turn the breaker back on.

Otherwise, follow the instructions below;

  • Open the ice machine as described above.
  • Push and hold the power button until the unit powers on.
  • Once unit has powered on, the screen will activate.
  • Close the front door of the machine, and replace the 2 screws.
  • Ensure the panel is thoroughly secured.

Manitowoc Ice Machine Not Turning On

This could be due to;

Interrupted power supply

If your machine is not turning on, it may not have no power supply. Check the main power switch and turn it on. To check if the power outlet is working or not, plug another device into the outlet and check for power. If it is also not getting power, then replace the fuse or reset the breaker.

The machine is not ON

Manitowoc ice machine does not operate with the power on, check whether the toggle switch is set to “Ice” or not. You should note that the switch is not positioned at “OFF” or “Clean”.

The damper is OFF

Check the damper position. If the damper is positioned down, your ice machine will turn off until the issue is fixed. The damper should be held in the upright and swinging freely.

All Manitowoc ice machine troubleshooting codes and their meanings

  • E01: Long Freeze Cycle.
  • E02: Long Harvest Cycle.
  • E03: Input Power Loss – When power to the Indigo ice machine has lost, the control board will log the event in the ELOG and determines the loss of power on power-up.
  • E04: High Condenser Temperature or Water Condenser Fault.
  • E05: High-Pressure Control Opened – The high pressure cutout switch (HPCO) has opened three times in a 4-hour period.
  • E07: Starving TXV Single Evaporator or Low on Charge. Ten consecutive occurrences where the difference of average evaporator inlet T3 and outlet T4 is greater than 12 degrees Fahrenheit in the last one minute of the freeze cycle.
  • E08: TXV Fault Single or Dual Circuit Evaporators.
  • E09: Flooding Evaporator Fault Single Evaporator/ Single Circuit.
  • E10: Flooding Evaporator Fault Dual TXV or Dual Circuit.
  • E11: Refrigeration Fault. The compressor discharge temperature didn’t increase by at least one-degree F and the evaporator temperature.
  • E12: Curtain Switch Fault. The machine is set for ice making and remains in bin full condition for more than 24 hours.
  • E15: Fan Cycle Control Fault – Low Liquid Line Temperature. If the liquid line temperature drops below 60 degrees Fahrenheit for a period of time exceeding continuously for a minute during the freeze cycle.
  • E16: Remote Condensing Unit Fault (CVD Only). If the liquid line temperature drops below 40 degrees F or exceeds 140 degrees F for more than a continuous minute during the freeze cycle.
  • E19: Ice Thickness Probe Fault. The monitored frequencies are out of the appropriate range. There might be a problem with the microphone.
  • E20: Water System Fault.
  • E21: T1 Fault -Temperature Sensor Issue.
  • E22: T2 Temperature Sensor Issue.
  • E23: T3 Temperature Sensor Issue.
  • E24: T4 Temperature Sensor Issue.
  • E25: Bin Level Probe Low Sensor Fault. Each thermistor reading is monitored continuously by using six-second average values. When a thermistor has a 6-second average value outside of the valid range for more than 10 continuous minutes, you will see this code.
  • E26: T6 or T7 Temperature Sensor Issue.
  • E27: T6 or T7 Temperature Sensor Issue.
  • E28: AUCS Fault – When the AUCS clean option is selected from the menu, the control checks for the presence of the AUCS board. If the AUCS is not detected, it signals as AUCS.
  • E29: USB communication error, no USB drive in port, or defective USB drive.
  • E30: USB download error related to a USB drive or a defective USB drive.
  • E31: Safe Mode. Safe mode allows the ice machine to operate for a period of time in the event of ITP sensor failure.
  • E32: RS485 Communication Fault. The device plugged into the RS485 port is not communicating with the control board and gateway
  • E33: Touchscreen Fault.
  • E34: Display Fault.
  • E36: Check Sum Error.
  • E37: Watch Dog Event.
  • E38: UI Comm Event

Manitowoc Ice Machine Not Harvesting

Below are some reasons why your ice maker is not harvesting ice

The timer hasn’t stopped

The harvest sequence cannot be initiated until a 6-minute freeze timer has elapsed. If ice forms before then, it will be held until the timer completes.

Ice thickness sensor is dirty or disconnected

Clean the sensor if it’s dirty. If the ice thickness sensor needs adjustment, make sure it’s adjusted so the water flow, not the ice, contacts the sensor to initiate a harvest.

Uneven ice fill

If the ice is thin at the top of the evaporator, continue reading for the solution further down in this post under the problem “shallow or incomplete cubes.”

Manitowoc Ice Machine Keeps Running

The main culprit, in this case, is a stuck open Dump Valve

It’s easy, disconnect the ice machine drain, careful not to make a mess. Start the ice machine and watch the water flow out of the ice machine. During the freeze cycle, once the compressor is on and water flows over the evaporator.

No water should be exiting the ice machine. If you notice water flowing to the drain, throughout the freeze cycle, the dump valve is stuck open.

Manitowoc Ice Machine Troubleshooting Wrench Light

The wrench light signals the harvest season as well as the freezing cycle. This happens in 1-second intervals after three 35-minutes harvest cycles. If it stops working, this could be due to a number of reasons;

  • Damaged bulb
  • Damaged control board
  • Faulty sensors
  • Faulty timer
  • Faulty wiring

Check each potentially defective part for continuity and replace it as needed.

Manitowoc Ice Machine Not Draining

The main cause of this is a stuck closed Dump Valve.

Inspect the water trough during the startup cycle. Water should fill the water trough, then quickly purge down the drain. If you do not notice water actually leaving the trough, this indicates the valve may be stuck closed.

If your specific model ice machine is currently calling for a purge, there should be voltage to the valve. A dump valve is normally closed and will only open when voltage is applied.

Manitowoc Ice Machine Not Pumping Water

Below are several reasons why the ice machine is unable to pump water;

No water supply

Start with ensuring you have a water supply to the machine.  Just because you have a water line hooked up, does not mean that water is always available.  It’s possible that another piece of equipment has been added to the line, that robs the ice machine of water.  Another reason could be that the lines are clogged with debris, due to line breakage.

Blocked water filter

Next, check the water filter, if your Manitowoc ice machine is equipped with one.  Water filters should be changed at least every 6 months but may need to be changed more frequently.  Part of an ice filter’s job is to take the debris out of the water, which will eventually clog the cartridge.  If in doubt, change the water filter and check pressures.

Clogged water inlet

If you are sure you have a water supply to the ice machine, next check the water inlet valve.  A water inlet valve can get trash in it, causing it to clog.  Or, the water inlet valve could have failed, not opening at all or not enough to fill the water trough.

The Manitowoc water inlet valve is normally closed, which means it will only open when power is supplied to the coil.  Check voltage during the water fill cycle, if the valve does not have power, then you may have a control board problem.

Leaking dump valve or water trough

Losing the water that is supplied to the ice machine can also cause an empty water trough.  This can be caused by a leaking dump valve or a water trough that is damaged or not properly installed. 

Check the dump valve by removing the drain and see if any water is coming out during the freeze cycle.  In addition, a water trough that is hanging loose or cracked will leak water into the ice storage bin.  Look for signs of water outside of the flood zone.

Faulty Water level sensor

Last, look at your water level sensor, to ensure that it’s sensing properly.  The board will only tell the inlet valve to open when the water level sensor is not satisfied.  If the water level light is on, then it’s telling the ice machine that there is water in the trough. 

If no water is visibly touching the sensor, then check for cleanliness or signs of water tracking from the bottom of the evaporator.  In most cases, replacement of the water level sensor is necessary, if it’s there is too much limescale, ensure it is thoroughly cleaned.

Interrupted power supply

Proper voltage must be supplied to the water pump for it to work efficiently.  If too low of voltage is supplied, the motor will not be strong enough to pump the water.  However, too high of voltage could cause the motor to burn up.  Checking to make sure you have the proper voltage at the ice machine is important for not only the water pump but all electrical ice maker parts.

Clogged tubing and impeller

Check the tubing and the impeller for debris.  Hard scale can build up in the impeller, causing it to not turn.  Also, debris can block the screen, keeping a constant water supply from being pumped. A broken impeller or screen must be repaired with an entirely new pump assembly.

Note: A pump exposed to prolonged blockage could cause the motor to burn up and become damaged.

Defective water pump

The water pump works by taking the water from the water trough, pushing up through the tubing, out and over the evaporator through the distribution tube.  It’s important for the water pump to be strong enough to push an even flow of water, but not too strong to cause the stream of water to miss cascading down the evaporator. 

Note: If a water pump is struggling it will become very warm and hot to the touch.  A water pump that is exceptionally hot is a sign that failure is imminent.

Manitowoc Ice Machine Not Dropping Ice

Below are some reasons why the ice machine is not dropping ice;

Dirty machine

A dirty machine can slow down the harvest cycle or impede ice from releasing. Clean and sanitize the ice machine following the instructions in the owner’s manual.

The Ice Machine isn’t level

Level the ice machine and ensure it sits flat on the floor for optimal performance.

Ambient room temperature is too warm

On air-cooled models, the air temperature must be at least 40 degrees Fahrenheit or 4 degrees Celsius. Make sure the room isn’t too hot.

The Water regulating valve is leaking

On water-cooled models, if the water regulating valve is leaking in harvest mode, it could cause a problem. Replace the valve.

Manitowoc Ice Machine Not Getting Cold and Freezing

If your ice maker is not making ice, clean and sanitize it as this may prevent it from working. then ensure it is level to enable it to produce ice.

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Next, check to see the air temperature inside is cold enough. The machine requires air cooling must be a minimum of 40 degrees Fahrenheit to produce ice. The water regulating valve should be fully sealed. If it is leaking, replace the valve.

Manitowoc Ice Machine Not Making Full Ice Cubes

  • The ice thickness sensor needs adjustment – See if the ice thickness sensor need adjustment.
  • The Water level is too high or low – Make sure the water trough level isn’t too high or too low.
  • The water temperature is too high – Ice machines require a cold water supply. Make sure there is not a hot water supply line into the machine.
  • The water filter is broken – The water filter might be too dirty or damaged. You’ll need to replace it.
  • The water pressure is too low – The water pressure into the machine must be 20-80 psi (137.9-551.5 kPA).
  • The water float valve and its filter screen are dirty. Either can cause shallow or incomplete ice cubes.
  • The ice machine isn’t level – Make sure the machine is level. The machine must sit flat on the floor for optimal performance.

How Long Does the Manitowoc Ice Machine Take to Make Ice?

The maximum freeze time is 60 minutes on S-Series and Indigo machines and 45 minutes on NEO® models. The harvest cycle begins automatically after time maximum freeze time ends. The maximum harvest cycle time is 3.5 minutes for a single evaporator and 7 minutes for multiple evaporators.

Note: The Manitowoc takes 24-hours to produce their maximum amount of ice. So a 600-lb ice machine will take 24 hours to produce 600 lbs of ice.

How to Clean the Manitowoc Ice Machine

The methods below are for cleaning and sanitizing the S-Series, Indigo Series, and NEO Series of Manitowoc ice machines.

Items Needed

  • Manitowoc Ice Machine Cleaner
  • Manitowoc Sanitizer (Approved by the EPA for COVID-19 cleaning)
  • Cleaning Cloths
  • Safety Goggles
  • Rubber Gloves
  • Soft Nylon Cleaning Brush/Sponge
  • Spray Bottle
  • Food-Safe OEM-Recommended Lubricant

Pre-cleaning steps

  • Be sure to read and follow all directions and recommended mixture ratios as stated in your ice machine’s user manual.
  • Do not mix Manitowoc ice machine cleaner and Manitowoc sanitizer.
  • Do not use sharp objects or force ice from the evaporator or any other major components. This could cause significant damage.
  • As stated above, cleaning and sanitizing should be completed every 6 months.

Cleaning an Ice Machine

  1. For easy access, remove the front door and top cover.
  2. Turn the switch to the OFF position once ice has fallen from the evaporator at the end of a Harvest cycle.
  3. Alternatively, you can wait for the ice to melt off the evaporator after turning off the ice machine.
  4. Remove all the ice from the bin/dispenser.
  5. Set the switch to “CLEAN.” Water will then flow through the water dump valve and down the drain.
  6. Once the water trough refills and water flows over the evaporator, you can then add the recommended amount of ice machine cleaner.
  7. Refer to your user’s manual to know how much to use for your specific S-Series model.
  8. The cleaning cycle will last approximately 35 minutes (80 minutes for S3300 models).
  9. Once it’s completed, place the switch in the OFF position, then disconnect the power to the ice machine.
  10. Remove the proper parts from your unit. Refer to your user’s manual to determine what needs to be removed before going on to the sanitizing steps.
  11. Create a cleaning solution by mixing the cleaner with warm water by following the recommended ratio in your user’s manual.
  12. Take half of this mixed solution and clean all of the removed components.
  13. Soak these parts in the solution for 5 minutes (or 15-20 minutes if there is heavy scaling).
  14. The solution will foam when it comes in contact with lime scale and mineral deposits, and once it has stopped foaming, you can use a soft brush, cleaning cloth, or sponge to clean off the deposits.
  15. Rinse all components with clean water.
  16. While these components are soaking, take the other half of the cleaning solution and clean all foodzone surfaces of the ice machine and bin.
  17. Use a brush, sponge, or cleaning cloth to clean areas such as the;
  18. Bin/Dispenser
  19. Base (above water trough)
  20. Plastic parts of evaporator, including the top, bottom and sides
  21. Side walls
  22. Once clean, rinse these areas well with water. Now you can begin the sanitizing process.

Sanitizing Procedure

  • Create a mixture of sanitizer and warm water. Follow the recommended ratio.
  • Taking half of the sanitizing solution, fill a spray bottle with it and liberally coat the parts with the solution.
  • You can also soak these components in the sanitizing solution.
  • Don’t rinse the components after sanitizing.
  • Use the other half of the sanitizing solution to spray down the foodzone surfaces of the ice machine and bin.
  • When sanitizing, pay attention to the same areas as before (Bin/Dispenser, Base, Plastic parts of evaporator (top, bottom and sides), and Side walls)

Note: Don’t rinse after sanitizing.

  • Reinstall all removed components and wait 30 minutes.
  • Restore power to the ice machine, and flip the toggle switch to “CLEAN.”
  • Allow the water trough to refill until the water flows over the evaporator. This will take approximately 3 minutes.
  • Add the recommended amount of Manitowoc Ice Machine Sanitizer to the water trough by pouring it between the evaporator and water curtain. Refer to your user’s manual for the proper amount to use.
  • Flip the toggle switch to the “ICE” position, then replace the front panel.
  • The ice machine will start making ice automatically after the sanitize cycle is done (approximately 35 minutes, or 80 minutes for the S3300 model).

Exterior Cleaning

  • Clean the area around your Manitowoc ice machine regularly, and clean up any fallen ice or water spills as they occur.
  • Dust and clean the outside of the ice machine as necessary with mild soap and water. Wipe with a clean cloth afterwards.
  • If your unit has stainless steel, you can use a stainless steel cleaner.
  • Never use steel wool or anything abrasive as this will damage the protective coating of stainless steel and allow for the possibility of rust.

Descaling and Disinfecting Your Manitowoc Ice Machine

  1. Descaling is the first step of the cleaning process and involves removing mineral deposits. We’ll address it in detail in the Descale section of Cleaning the Interior of an Ice Machine below.
  2. Disinfecting is the process of using chemicals to kill microorganisms like bacteria, viruses, and fungi. During this process, any remaining algae, mold or slime should be removed.

Important Notes:

  • Manitowoc recommends two annual cleanings. The machine should be wiped down as needed due to spillage or any noticeable internal or external dirtiness.
  • You can use a diluted solution of bleach and water. Ensure the bleach you use has an EPA registration number (this means it is qualified for use on food contact surfaces like ice machine components).
  • Bleach will need to be diluted before you use it, and there is a different rate of dilution for disinfecting and sanitizing. Dilution rates may vary depending on the product you use.
  • DO NOT mix bleach with other cleaners. The combination can produce harmful, toxic fumes that can cause respiratory distress.

Why Is My Manitowoc Ice Machine Smelling Damp?

You may even notice that the ice maker smells like mildew, which happens when old, unused ice is exposed to food particles and develops mold. Throw away all the old ice and clean the ice machine.

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The slime and mold also form because the ice-making process is exposed to the air. The air, is filled with many contaminants, including mold spores and bacteria that can lead to a dirty ice machine.

Lastly, as water flows over the ice making surface of your ice machine, these contaminants spread through the ice machine. Other airborne contaminants, like yeast, will feed the mold until it matures and begins to change color.