Icematic N21, Service Manual

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GB
24
Electric Controls............................... ON OFF
Conctats 3-4 evaporator thermostat...
■
Conctats 3-2 evaporator thermostat...
■
Bin thermostat ....................................
■
Conctats COM-NO timer microswitch
■
Conctats COM-NC timer microswitch.
■
Pressure control .................................
■
II° PORTION HARVEST CYCLE
Electrical components (Loads) ....... ON OFF
Compressor ........................................
■
Fan motor ...........................................
■
Hot gas valve......................................
■
Water inlet valve .................................
■
Water pump ........................................
■
Relay coil ............................................
■
Timer motor ........................................
■
Electric Controls............................... ON OFF
Conctats 3-4 evaporator thermostat...
■
Conctats 3-2 evaporator thermostat...
■
Bin thermostat ....................................
■
Conctats COM-NO timer microswitch
■
Conctats COM-NC timer microswitch.
■
Pressure control .................................
■
OPERATING CHARACTERISTICS
On air cooled models during the freezing cycle the dis-
charge pressure is between 9 and 7 bars.
At the same time the suctionpressure will gradually
decline, reaching its lowest point just before harvest.
Compressor amps experience a similar drop. On water
cooled, the discharge pressure is maintained constant
during the freeze cycle by the water regulating valve at 8
bars.
However, suction pressure and compressor amps will still
decline as the machine freezes ice.
COMPONENTS DESCRIPTION
A. EVAPORATOR THERMOSTAT
The evaporator thermostat with its sensing bulb intimate-
ly in contact with the refrigerant outlet tube from the evap-
orator, senses the evaporating refrigerant temperature
(wich declines in the one reaches the pre-set value, it
switches its contacts from 3-4 to 3-2 to activate the finish-
ing cycle (2nd phase) which has a pre-set extension
determined by the large diameter lobe of the timer cam.
B. BIN THERMOSTAT
The bin thermostat, which has its sensing bulb downward
into the storage bin, shuts-OFF automatically the icemak-
er when the ice storage bin is filled and ice contacts its
bulb. Being it connected in series with the front
microswitch of the timer, it causes the unit shut-off only at
the end of the freezing cycle, when the ice cubes are com-
pleted.
After ice is removed from the bin and its bulb warm-up it
allows the unit to restart from the beginning of the harvest
cycle which, in the circumstance, is more likely a water fill-
ing cycle.
C. TIMER
Equipped with two microswitches which plungers ride one
timer cam, the timer is located inside the control box. The
function of the timer begins when activated by the cube
size control (evap. thermostat).
The large diameter lobe, determines the 2nd freezing
cycle portion length, while the cam small diameter lobe,
determines the time cycle for the harvest sequence. The
timer cam can be adjusted to vary the defrost time as
required.
WARNING. Never set the defrost time for longer
than 4 minutes as this will jeopardize the com-
pressor motor windings.
It goes without saying that an extension of the defrost
period will directly reduce the timed portion of the freezing
cycle and and viceversa.
Consequently any variation made at the timer cam setting
requires a compensation adjustment, very fine and very
accurate, of the evaporator thermostat.
D. HI PRESSURE CONTROL
Used on water cooled ice makers it functions to maintain
the head pressure within the present values of 8 and 10
bars, by intermittently activating the water inlet valve to
the condenser (in the water cooled models).
E. HI TEMPERATURE SAFETY THERMOSTAT
(Water air cooled models)
Fastened directly onto the refrigerant liquid line and elec-
trically connected upstream all other controls, this safety
thermostat shut-off the icemakers when senses that the
temperature at the liquid line has rised to the limit of 65°C.
F. WATER SPRAY SYSTEM
It consists of on spray bar with several spray nozzles on
its extension.