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On model MV 50 the release of the ice plate from
the second evaporator will cause the restart of
the machine in the freezing cycle.
NOTE: In case the P.C. Board does not
receive the pulse from the second magnetic
switch, after 40 second from the first pulse, it
will switch the unit from defrost to freezing
cycle.
The harvest cycle lasts about 1.5
÷
2 minutes.
CONTROL SEQUENCE
At the start of the freezing cycle, the contacts of
the magnetic switch mechanically operated by
the actuator plate of the deflector cover are
closed, thereby - via electronic control board -
closing the circuit to the main contactor coil and
consequently to the compressor and fan motors
and to the water pump motors.
Then, as the ice thickness reaches the value that
corresponds to the full cube size, the film of water
that constantly cascades over the slab of ice
formed on the evaporator, arrives to establish a
contact between the two fingers (energised at
low voltage) of the ice sensor control, located on
the front upper right side of the evaporator. If the
contact between the two fingers of the ice sensor
remains established - by the film of water - for
more than 10 seconds, a small relay of the
electronic board, get energized, controlling -
simultaneously both the hot gas valve and the
water drain valve.
NOTE: in case of failure of ice level sensor,
the P.C. Board turns - on automatically the
unit into the defrost cycle when the freezing
cycle reaches 40 minutes.
At this point, the unit initiates the defrost cycle.
The hot gas circulating into the evaporator
serpentine causes a slight melting of ice cubes
which get released from their molds. Once entirely
released the ice cubes drop simultaneously into
the ice storage bin below; by doing so they move
apart from the evaporator bottom end the plastic
deflector. This plastic deflector has on its side a
magnetic switch that on account of the deflector
swinging motion, caused by the ice while dropping
in the bin, opens and closes their contacts. This
will, in turn, disactivate the relay contacts that
controls the hot gas and water drain valve which
get deenergized allowing the unit to start a new
freezing cycle.
When the ice bin is full of ice, the last batch of ice
cubes released from the evaporator accumulates
to keep the bottom end of the plastic deflector in
open position; with the magnetic switch contacts
open for longer than 30'’ the entire unit stops.
On model MV 50 in case one or both the ice
slabs, released from the evaporator, are
maintaining in open position their corresponding
deflector for longer than 30 seconds, with the
consequent opening of the magnetic switch for
the same extension of time, the P.C. Board
cause the stopping of the unit operation. This
normally occures in the full ice storage bin
situation which are signalled by the
simoultaneous glowing of the corresponding LED.
The machine will restart when the ice deflector
will be back in its normal vertical position (both for
model MV50) provided that 3' are elapsed from
unit stop. If not the machine will delay its restart till
3' are elapsed with the blinking of the green LED.
