Manitowoc J-1300, Руководство по обслуживанию

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Section 6 Electrical System
6-50
Ice Thickness Probe
(Harvest Initiation)
GENERAL
The ice thickness probe has been changed from a dual
probe to a single probe. This eliminates the
possibility of scale or slime forming between the
probes and causing a premature harvest cycle.
Ice Thickness Probes
HOW THE PROBE WORKS
Manitowoc’s patented electronic sensing circuit does
not rely on refrigerant pressure, evaporator
temperature, water levels or timers to produce
consistent ice formation.
As ice forms on the evaporator, water (not ice)
contacts the ice thickness probe. After the water
completes this circuit across the probe continuously
for 6-10 seconds, a harvest cycle is initiated.
Since original production, a harvest cycle could be
initiated one of two ways:
•
Completing the circuit (shorting) across terminals
1C and 1D on the control board
•
Completing the circuit (shorting) from terminal
1C on the control board to a cabinet ground
anywhere in the ice machine
The improved, single probe design uses this second
method.
FREEZE TIME LOCK-IN FEATURE
Since original production, the ice machine control
system has incorporated 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. If water contacts the ice
thickness probe during these six minutes, the harvest
light will come on (to indicate that water is in contact
with the probe), but the ice machine will stay in the
freeze cycle. After the six minutes are up, a harvest
cycle is initiated. This is important to remember when
performing diagnostic procedures on the ice thickness
control circuitry.
To allow the service technician to initiate a harvest
cycle without delay, this feature is not used on the
first cycle after moving the toggle switch OFF and
back to ICE.
MAXIMUM FREEZE TIME
Since original production, The control system has
included a built-in safety which will automatically
cycle the ice machine into harvest after 60 minutes in
the freeze cycle.
INSTALLATION OF NEW PROBE
ON OLD STYLE CONTROL BOARD
1. Remove the old probe from the mounting bracket.
2. Snap the new probe into the mounting bracket.
3. Connect the single wire on the probe to terminal
1C on the control board.
NOTE: No wire is attached to terminal 1D on the old
style control board.
Installing New Ice Thickness Probe
OLD STYLE DUAL PROBE
SV1589
SV1594
NEW STYLE SINGLE PROBE
ICE THICKNESS PROBE
CONTROL BOARD
EVAPORATOR