Scotsman MC 45 Manual de servicio descargar pdf (Pagina 22)

Page 22

Freeze Cycle

Average Discharge

Pressure A/C: 16÷18 bars (225÷250 psig)

Average Discharge

Pressure W/C: 17 bars (240 psig)

Suction Pressure End

Freeze Cycle: 1.6÷1.7 bar (22÷24 psig)

REFRIGERANT CHARGE (R 404 A)

Air Cooled Water Cooled

MC 15 640 gr 500 gr

MC 45 1300 gr 700 gr

MC 45 (60 Hz) 1040 gr 560 gr

NOTE. Before charging the refrigerant system

always check the type of refrigerant and

quantity as specified on the individual ice

machine dataplate.

The refrigerant charges indicated are related

to average operating conditions.

WARNING. As R 404 a is a band of different

types of refrigerants it is imperative to

charge the system only in liquid phase in

order to avoid to alter their mix-up

percentage.

COMPONENTS DESCRIPTION

A. EVAPORATOR TEMPERATURE

SENSOR

The evaporator temperature sensor probe,

located in contact with the evaporator serpentine,

detects the dropping of the evaporator tempera-

ture during the freezing cycle and signals it by

supplying a current flow to the micro processor of

P.C. BOARD.

According to the current received, the evaporator

sensor supplies power to the P.C. BOARD first,

when it reachs 0

C (32

F), second at -15

C (5

F);

in this second case it supply power to the electronic

timer built into the P.C. BOARD so that it may

take control of the fength of the 2nd phase of

freezing cycle.

The length of the timed phase is pre-f ixed 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 occures usually in the mid period

of the freezing cycle and signals the switching

from the first to the second phase of the freezing

cycle.

NOTE. Whenever, after 15 minutes from the

beginning of the freezing cycle, the

evaporating temperature have not yet

reached the value of 0

C (32

F), the P.C.

BOARD switches OFF the machine with the

BLINKING of RED LED.

B. 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 tempera-

ture 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 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.

In case the condenser temperature rises and

reaches 70°C (1 60°F) - on air cooled models - or

62°C (145°F) - on water cooled models - the

current arriving to the micro processor is such to

cause an immediate and total stop of the machine

operation.

C. AMBIENT TEMPERATURE SENSOR

The probe of this sensor, located in the front of

the ice maker condenser (Air cooled version) and

on 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 elaborated by the micro processor in

order to extend or shorten the defrost cycle

length (longer in cold ambient situations, shorter

in warm ones.

D. ICE RIN 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 into the bin.

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