Electrolux BEVERAGE CENTER II, Service Manual

Page: 35 / 77

34
AIR CIRCULATION
AUTOMATIC DEFROST MODELS
Principals Of Automatic Defrost Operation
Automatic defrost refrigerators operate on the principle
that moisture or frost transfers or migrates to the coldest
surfaces (evaporator) in the freezer compartment. For
example, a small amount of water spilled from an ice cube
tray in the freezer compartment will freeze immediately.
However, this ice in time will evaporate and transfer to
the colder surfaces of the freezer evaporator coil.
Air Circulation Patterns
Automatic defrost models have a single evaporator in the
freezer compartment, and have forced air cooling in the
freezer and refrigerator compartments.
The “fin and tube” aluminum type evaporator is located
on the back wall of the freezer compartment. A circulating
fan (suction type) pulls air from the air return in the
freezer and refrigerator compartments up through the
evaporator surfaces from the bottom. The cold air is
forced into a fan cover and discharged into the freezer
and refrigerator compartments as shown in Figure D1.
Cold air for the refrigerator compartment flows from the
evaporator through an air duct located in front of the
evaporator cover and into the food compartment through
air ducts on the Control Box. Return air from the
refrigerator compartment flows through an opening on
each side of the control housing, located all the way to
the back next to the liner, through a 90° air return duct
and back to the evaporator.
Cold air for the freezer compartment flows from the
evaporator through an air discharge grill around the fan
motor and into the freezer compartment. Return air from
the freezer compartment flows through the louvers
located on the back wall near the bottom of the freezer
compartment, just in front of the evaporator.
The air circulating fan operates only when the
compressor is running. During the defrost period, the
compressor and circulating fan do not operate. The
automatic defrost timer opens the electrical circuit to the
fan motor and compressor.
Figure D1