Sequence Of Operation; Initial Start-Up Or Start-Up After Automatic Shut-Off; Freeze Sequence; Harvest Sequence - Manitowoc S Installation, Use & Care Manual

Ice Machine Operation

Sequence Of Operation

NOTE: The toggle switch must be in the ice position and
the water curtain/ice dampers must be in place on the
evaporator before the ice machine will start.
INITIAL START-UP OR START-UP AFTER

AUTOMATIC SHUT-OFF

1. Water Purge
Before the refrigerant compressor starts, the water pump
and water dump solenoid energize to purge the ice
machine of old water. This feature ensures that the ice
making cycle starts with fresh water.
Single evaporator models energize the harvest valve(s)
and air compressor (when used) at the end of the water
purge and they remain energized during refrigeration
startup.
2. Refrigeration System Start-Up
The compressor, condenser fan motor and water fill
valve energize and 5 seconds later the harvest valve(s)
and air compressor(s) de-energize.
The fan motor is wired through a fan cycle pressure
control and will cycle on and off when the room
temperatures is below 70 F (21 C) .

FREEZE SEQUENCE

3. Prechill
The compressor lowers the temperature of the
evaporator(s) before the water pump is energized. The
water fill valve will remain energized until water contacts
the water level probe.
4. Freeze
The water pump(s) energizes and water flows over the
evaporator. After water contacts the water level probe
the water fill valve de-energizes. The water fill valve will
cycle on and off one more time.
The freeze cycle continues until the six minute freeze
lock expires and enough ice has formed to allow water to
contact the ice thickness probe. After approximately 10
seconds of continual water contact, the harvest
sequence is initiated.
NOTE: Freeze lock is bypassed after moving the toggle
switch from OFF to ICE position for the first cycle only.
3-2

HARVEST SEQUENCE

5. Water Purge
The air compressor (when used) and the harvest
valve(s) open at the beginning of the water purge to
divert hot refrigerant gas into the evaporator.
The water pump continues to run, and the water dump
valve energizes to purge the water in the water trough.
Single evaporator models energize the water fill valve for
the last 15 seconds of the water purge cycle.
6. Harvest
The air compressor (when used) remains energized and
the harvest valve(s) remains open. The refrigerant gas
warms the evaporator causing the cubes to slide, as a
sheet, off the evaporator and into the storage bin.
Single evaporator models - The sliding sheet of cubes
opens the water curtain and bin switch.
The momentary opening and re-closing of the bin switch
terminates the harvest sequence and return to the
freeze sequence (Step 3 - 4.)
Multiple evaporator models - The sliding sheet of
cubes opens the ice damper and bin switch. The
momentary opening and re-closing of the bin switch de-
energized the harvest valve for the evaporator. When all
of the bin switches have opened and closed the ice
machine will terminate the harvest sequence and return
to the freeze sequence (Step 3 - 4.)
AUTOMATIC SHUT-OFF
7. Automatic Shut-Off
When the storage bin is full at the end of a harvest
sequence, the sheet of cubes fails to clear the water
curtain/ice damper and will hold it open. After the water
curtain/ice damper is held open for 30 seconds, the ice
machine shuts off. The ice machine remains off for 3
minutes before it can automatically restart.
The ice machine remains off until enough ice has been
removed from the storage bin to allow the ice to fall clear
of the water curtain or all of the ice dampers. As the
water curtain/ice dampers swing back to the closed
position, the bin switch re-closes and the ice machine
restarts (steps 1 - 2), provided the 3 minute delay period
is complete.
Section 3
Part Number 000000966 03/09