Manitowoc STH042 4/16, Technician'S Handbook

Page: 61 / 146

Part Number STH042 4/16 61
Ice Machine Does Not Cycle Into Harvest
when Water Loses Contact with the Harvest
Float Switch
NOTE: The ice machine will make a thick or double
slab when a new freeze cycle is started with ice already
present on the evaporator.
Two of the most common scenarios are:
• Power is cycled off/on with ice on the evaporator.
• The ice damper/bin switch is opened/closed in the
harvest cycle before the ice releases.
Remove all ice from the evaporator before starting
diagnostic procedures.
Freeze Time Lock-In Feature
The ice machine control system incorporates a freeze
time lock-in feature. This prevents the ice machine from
short cycling in and out of harvest. The control board
locks the ice machine in the freeze cycle for six minutes.
After six minutes a harvest cycle can be initiated. To allow
the service technician to initiate a harvest cycle without
delay, this feature is not used on the first cycle after
pressing the power button OFF and back to ON.
Step 1 Disconnect power to the ice machine, remove
the electrical panel to allow viewing of the control board
lights and pull the wire connector for the harvest float
switch through the bulkhead and disconnect. Attach
a jumper wire to the wire terminals connected to the
control board.
Step 2 Bypass the freeze time lock-in feature by
pressing the power button to cycle the ice machine on.
Wait until water flows over the evaporator, then refer to
chart.
Result Correction
10 seconds into the freeze cycle
the ice machine cycles from freeze
to harvest and the control board
harvest light energizes. Refer to Float Switch
Diagnostics.
The harvest light stays off and the
ice machine remains in freeze. Proceed to Step 3