ambient temperature as detailed in Table C. Page 18.
The electrical components in operation during this phase are:
COMPRESSOR
WATER PUMP
WATER INLET SOLENOID VALVE
HOT GAS SOLENOID VALVE
The incoming water, passing through the water inlet valve and the flow control, runs over the evaporator platen and then flows by gravity through the dribbler holes down into the sump/reservoir.
The water filling the sump/reservior forces part of the surplus water from the previous freezing cycle to go out to the waste through the overflow pipe. This overflow limits the level of the sump water which will be used to produce the next batch of ice cubes.
Meanwhile, the high pressure, high temperature refrigerant, discharged from the compressor, flows through the hot gas valve directly into the evaporator serpentine by-passing the condenser.
The hot gas circulating into the serpentine of the evaporator warms up the copper moulds causing the defrosting of the ice cubes. The ice cubes, released from the cups, drop by gravity onto a slanted cube chute, then through a curtained opening they fall into the storage bin.
NOTE: The length of the defrost cycle, factory set, can vary in accordance with the actual ambient temperature (as shown on Table C). Page 18. For instance, in a high ambient temperature situation it can be reduced to recover some of the time spent for the longer freezing cycle.
At the end of the defrost cycle, both the hot gas and the water inlet valves close, so the machine initiates another freezing cycle.
11.4 Operation - Control Sequence
At the start of the freezing cycle, the evaporator temperature sensor controls the length of the first part of the freezing cycle. As it reaches a pre-determined temperature, it supplies a low voltage current to the P.C. BOARD in order to activate the electronic timer which takes over the control of the freezing cycle for a pre-fixed time according to the DIP SWITCH keys setting (see Table B). Page 18.
NOTE: The evaporator temperature sensor, factory pre-set, is the same for all the models and is not adjustable in the field.
Once completed the freezing cycle 2nd phase the system goes automatically into the defrost cycle which has also a pre-fixed length that can vary depending upon the actual ambient temperature as shown in Table C. Page 18.
At completion of the defrost cycle the P.C. BOARD command the unit to start again a new freezing cycle.
12.Components Description
12.1 Evaporator Temperature Sensor
The evaporator temperature sensor probe, located in contact with the evaporator serpentine detects the dropping of the evaporator temperature during the freezing cycle and signals it by supplying a current flow to the micro processor of the P.C. BOARD.
According to the current received, the evaporator sensor supplies power to the P.C. BOARD first, when it reaches 0°C (32°F), second at -15°C (5°F); in this second case its supply power to the electronic timer built into the P.C. BOARD so that it may take control of the length of the 2nd phase of freezing cycle.
The length of the timed phase is pre-fixed by the setting of the keys 1, 2, 3 and 4 of the DIP SWITCH.
The activation of the electronic timer (-15°C -5°F) is monitored by the lighting up of the RED LED placed in the front of the P.C. BOARD. This lighting up occurs usually in the mid period of the freezing cycle and signals the switching from the first to the second phase of the freezing cycle.
12.2 Condenser Temperature Sensor
The condenser temperature sensor probe, located within the condenser fins (air cooled version) or in contact with the tube coil (water cooled version) detects the condenser temperature variations and signals them by supplying current, at low voltage, to the P.C. BOARD.
In the air cooled versions, in relation to the different current received, the micro processor of the the P.C. BOARD supplies, through a TRIAC, the power at high voltage to the fan motor so to cool the condenser and to reduce its temperature rises and reaches 75°C (170°F) the current arriving to the micro processor is such to cause an immediate and total stop of the machine operation.
12.3 Ambient Temperature Sensor
The probe of this sensor, located in the front of the ice maker condenser (air cooled version) and in the water supply line to the condenser (water cooled version) has the function to detect the ambient or the water temperature and, by changing its own electrical resistance, supplies a different current flow to the P.C. BOARD.
This different current flow received by the P.C. BOARD, is processed by the micro processor in order to extend or shorten the defrost cycle length (longer in cold ambient situations, shorter in warm ones).
12.4 Ice Bin Level Light Control
The electronic ice bin level control, located into the storage bin, has the function to stop the operation of the ice machine when the light beam between the light source and the sensor is interrupted by the ice cubes stored in the bin. When the light beam is interrupted the RED LED located in the front of the P.C. BOARD goes off; in case the light beam is constantly interrupted for more than 60 seconds, the ice machine stops with the glowing-up of the 2nd YELLOW LED to monitor the situation of ice bin full. The 60 seconds of delay prevent that an ice scoop movement or the ice dropping through the ice chute (interrupting for a while the light beam) can stop the operation of the unit.
As soon as the ice is scooped out (with the resumption of the light beam between the two infrared sensor of ice level control) the RED LED is lighted up and after 6 seconds the ice machine restarts again with the extinguishing of the 2nd YELLOW LED.
12.5 E.P.C. Board (Data processor)
The P.C. BOARD, fitted in its plastic box located in the front of the unit, consists of two separated printed circuits one at high and the other at low voltage integrated with a program selector, of two fuses one on power in (100m A) and one on power out (16 A) of five aligned LEDS monitoring the operation of the machine, of two extra monitoring RED LEDS, of one DIP SWITCH with ten keys, of two small plugs located on its back side, of input terminals for the leads of the sensor probes and input and output terminals for the leads of the ice maker electrical wires. The P.C. BOARD is the brain of the system and it processes, through its micro processor, the signals received from the four sensors in order to control the operation of the different electrical components of the ice maker (compressor, water, pump, solenoid valves, etc.).
By turning the program selector it is possible to put the unit in the following different situations.
CLEANING/RINSING: The water pump is the only electrical component in operation and it must be used during the cleaning or the rinsing procedure of the water system of ice machine.
STAND BY: The unit remain under electrical power but OUT of operation. It can be used by the service engineer in order to stop the unit during
