Theory Of Operation - KitchenAid KUWS24RSBS Technical Education

GENERAL
There are three variations of one core platform
available: a wine cellar, a beverage center and
an all refrigerator. All units share the same
basic cooling system with only slight differenc-
es in airflow inside the cabinet. The fan forced
evaporator is frost-free, using a conventional
compressor run defrost timer, defrost heater,
defrost bimetal and thermal fuse. All three
units use a single mechanical cold control.
UW/BC: On the beverage center and wine cel-
lar the separate temperature zones are main-
tained through the amount of airflow to each
zone. On these units the thermostat tube is
coiled in the evaporator compartment, on the
right-hand side above the evaporator. The
thermostat bulb on the wine cellar and bever-
age center is coiled on the right side above
the evaporator. UR: The thermostat bulb on
the all-refrigerator is coiled in the lower right
corner below the evaporator. The thermostat
bulb is the cold control's sensing point that
determines run time.
AIRFLOW
The UR has one temperature zone. The UW
has two temperature zones and the BC has
three temperature zones. It is important to
remember that on the BC & UW, the coldest
zone will be at the top and the warmest zone
at the bottom. This is due to the fan forced
evaporator airflow pattern. Airflow from the
evaporator is first directed into the top of the
compartment. The bottom zone on the BC
and UW, is cooled primarily by conduction
and to a smaller degree, air migration past
the separator. The middle zone on the BC
is cooled from a small amount of air migrat-
ing from the top zone. The warm air return
is located approximately in the center of the
evaporator cover on all models.

THEORY OF OPERATION

AmBIENT THERmOSTAT
The beverage center and wine cellar have
a 7 watt liner heater located just under the
liner in the bottom of the lower compartment.
An ambient thermostat mounted above the
compressor controls the heater. The ambi-
ent thermostat bulb is routed into the bottom
of the cooling compartment. The thermostat
closes to energize the heater if the lower zone
gets too cold. The ambient thermostat is not
adjustable.
TEmPERATURE
DISPLAYS (UW, BC)
The beverage center and wine cellars have a
temperature display for each zone. 12 volts
AC is supplied to the display board from a
transformer in the unit compartment. The
displays are only temperature displays and
have nothing to do with any cooling function.
A thermistor is used to sense temperature
for each zone. The thermistor for the bottom
zone is located inside the lower portion of the
separator. The thermistor for the top zone
on the wine cellar, (mid zone on beverage
center), is located in the upper portion of the
separator. The thermistor for the beverage
center upper zone is located on the inside
of the 2-piece evaporator cover. It is on the
right-hand side.
The mid temperature for the bottom zones on
either unit are 60º Fahrenheit plus or minus
5 degrees. The mid temperature for the mid
zone on the beverage center and the top zone
on the wine cellar is 45º Fahrenheit plus or
minus 5 degrees. The mid temperature for the
top zone on the beverage center is 38º Fahr-
enheit plus or minus 5 degrees.
3-1
(UW, BC)