Ice Maker Sequence of Operation

Introduction to Sequence of Operation

• The sequence of operation is a step-by-step process that a machine goes through to complete a task, in this case, making ice.
• Understanding the sequence of operation is crucial for troubleshooting.
• The sequence of operation can be found in the Technician's Handbook.

Purge Cycle

• The purge cycle is the first step in the sequence of operation.
• During the purge cycle, the water pump and dump valve are energized to remove any water left in the tray.
• This ensures that the machine starts with fresh water.

Equalization Mode

• After the purge cycle, the machine enters equalization mode for 5 seconds.
• During equalization mode, the harvest valve and air pump (if equipped) are energized to equalize pressures in the system.
• This makes it easier for the compressor to start up.

Start Sequence

• After equalization mode, the machine enters the start sequence.
• During the start sequence, the harvest valve is energized for 5 seconds, and the air pump (if equipped) and contactor coil for the compressor and fan are energized.

Pre-Chill Cycle

• After the start sequence, the machine enters the pre-chill cycle.
• The pre-chill cycle lasts for 2 minutes on the initial startup and 30 seconds on subsequent cycles.
• During the pre-chill cycle, the water fill valve is energized, and the water level probe is monitored.

Freeze Cycle

• After the pre-chill cycle, the machine enters the freeze cycle.
• During the freeze cycle, the water pump, water fill valve, and contactor coil for the compressor and fan are energized.
• The freeze cycle lasts for a maximum of 35 minutes.

Harvest Cycle

• After the freeze cycle, the machine enters the harvest cycle.
• During the harvest cycle, the harvest valve, air pump (if equipped), and contactor coil for the compressor and fan are energized.
• The harvest cycle lasts for a maximum of 7 minutes.

Water Assist Function

• If the ice sheet doesn't drop after 3.5 minutes, the machine enters the water assist function.
• During the water assist function, the water solenoid valve is energized, and water is circulated over the evaporator to help free the ice sheet.

Troubleshooting

• The sequence of operation can help troubleshoot issues with the machine.
• Checking the energized chart can help identify where in the sequence the machine is and what components should be energized.
• Inputs and outputs can also be checked to determine where the machine is in the sequence.

Scenario 1: Machine Not Getting Water

• Check the water level probe to see if it's sensing water.
• If the probe is not sensing water, check the water inlet valve and supply.
• If the probe is sensing water, check the water level probe itself.

Scenario 2: Machine Not Harvesting

• Check the harvest valve to see if it's open or closed.
• Check the inputs and outputs to determine where the machine is in the sequence.
• Check the energized chart to see if the harvest valve should be open.

Scenario 3: Long Freeze with Water in the Trough

• Check the water pump to see if it's working correctly.
• Check the inputs and outputs to determine where the machine is in the sequence.
• Check the energized chart to see if the water pump should be running.

Conclusion

• The sequence of operation is a crucial tool for troubleshooting issues with the machine.
• Understanding the sequence of operation can help identify where in the process the machine is and what components should be energized.
• The Technician's Handbook provides more information on troubleshooting and the sequence of operation.### Upcoming Topics
• October: Cleaning a heavily scaled ice machine
• November: Quiet Cube and Remote Headmaster operation, troubleshooting
• December: Indigo and Indigo Next event log navigation, troubleshooting techniques

Quiz and Swag Bundle Giveaway

• Take the quiz within 2 hours of the original webcast or recorded webcast views
• Employees of Manitowoc Ice are not eligible
• Only one quiz submission per person
• Winners will be notified by email address
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• Swag bundle includes: hat, tote bag, tape measure, and selfie light
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Introduction to Sequence of Operation

• The sequence of operation is a step-by-step process that a machine goes through to complete a task, in this case, making ice.
• Understanding the sequence of operation is crucial for troubleshooting.

Purge Cycle

• The purge cycle is the first step in the sequence of operation.
• During the purge cycle, the water pump and dump valve are energized to remove any water left in the tray.
• This ensures that the machine starts with fresh water.

Equalization Mode

• After the purge cycle, the machine enters equalization mode for 5 seconds.
• During equalization mode, the harvest valve and air pump (if equipped) are energized to equalize pressures in the system.
• This makes it easier for the compressor to start up.

Start Sequence

• After equalization mode, the machine enters the start sequence.
• During the start sequence, the harvest valve is energized for 5 seconds, and the air pump (if equipped) and contactor coil for the compressor and fan are energized.

Pre-Chill Cycle

• After the start sequence, the machine enters the pre-chill cycle.
• The pre-chill cycle lasts for 2 minutes on the initial startup and 30 seconds on subsequent cycles.
• During the pre-chill cycle, the water fill valve is energized, and the water level probe is monitored.

Freeze Cycle

• After the pre-chill cycle, the machine enters the freeze cycle.
• During the freeze cycle, the water pump, water fill valve, and contactor coil for the compressor and fan are energized.
• The freeze cycle lasts for a maximum of 35 minutes.

Harvest Cycle

• After the freeze cycle, the machine enters the harvest cycle.
• During the harvest cycle, the harvest valve, air pump (if equipped), and contactor coil for the compressor and fan are energized.
• The harvest cycle lasts for a maximum of 7 minutes.

Water Assist Function

• If the ice sheet doesn't drop after 3.5 minutes, the machine enters the water assist function.
• During the water assist function, the water solenoid valve is energized, and water is circulated over the evaporator to help free the ice sheet.

Troubleshooting

• The sequence of operation can help troubleshoot issues with the machine.
• Checking the energized chart can help identify where in the sequence the machine is and what components should be energized.
• Inputs and outputs can also be checked to determine where the machine is in the sequence.

Scenario 1: Machine Not Getting Water

• Check the water level probe to see if it's sensing water.
• If the probe is not sensing water, check the water inlet valve and supply.
• If the probe is sensing water, check the water level probe itself.

Scenario 2: Machine Not Harvesting

• Check the harvest valve to see if it's open or closed.
• Check the inputs and outputs to determine where the machine is in the sequence.
• Check the energized chart to see if the harvest valve should be open.

Scenario 3: Long Freeze with Water in the Trough

• Check the water pump to see if it's working correctly.
• Check the inputs and outputs to determine where the machine is in the sequence.
• Check the energized chart to see if the water pump should be running.