Whirlpool 4322658A, Manual

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3-1
THEORY OF OPERATION
The ice maker loads, the motor, heater, and
water valve, are still controlled by the stamped
circuit module, which is part of the ice maker.
The electronic control will check periodically
to see if the ice maker is at the home position,
(when the ejector stops at the 2 o’clock posi-
tion). If the ejector is at the home position, the
relay will deenergize, and remove power from
the ice maker until the next harvest.
To improve functionality and reliability, some
important differences exist between the new
In-Door Ice system, and the earlier mechani-
cal-type ice making systems.
The first is that a harvest can only begin if the
freezer door is closed, and previous harvest
conditions are also met (ejector at home). If
the bin is full, and ice is removed, which low-
ers the ice level, it may take up to 5 minutes
before a harvest starts.
To prevent an early harvest from occurring af-
ter the last harvest is completed, a minimum
of 50 minutes must pass before another har-
vest will be initiated. Closing the receiver’s
shutoff slide covers the sensor and prevents
the ice maker from harvesting ice.
The In-Door Ice control contains two diagnos-
tic routines. One is an optics test, and the other
is a component test. There are two optics tests:
one for the original style optics, and the other
for the 2002 design optics:
1.a) Original Optics —An optics circuit test is
run when the freezer door switch is ac-
tuated three times, and the freezer door
is closed to allow a path for the optics
beam to reach the receiver.
b) 2002 Design Optics —An optics circuit
test is run any time the freezer door is
opened.
2. Component Test —A component test is
run on power-up when the freezer door
is closed.
Both routines provide visual feedback as to the
result of the diagnostic. All other system en-
hancements are transparent during the ice
making system operation.
The new ice making system consists of the fol-
lowing: an ice maker with an integrated con-
trol module, an electronic ice level sensor, an
external water valve, and a freezer door com-
partment-mounted ice storage bin.
The ice maker control module is a stamped
circuit that provides power and control for the
ice making loads, which consist of the motor,
heater, and water valve.
The ice harvesting process begins when the
ice maker thermostat closes and signals that
the harvest temperature has been reached.
The closed thermostat applies power to the ice
maker motor and to the heater. As the heater
melts the outer layer of the ice, the motor ro-
tates a rake, which sweeps the ice cubes out
of the mold, and into the storage bin.
Due to the placement of the storage bin on the
freezer door instead of on the cabinet, the
sensing of the ice level is quite different from
the earlier mechanical (bail arm) contact
method. The mechanical arm has been re-
placed by an electronic control that performs
this function, and two additional functions. It
controls power to the ice maker, and performs
system diagnostics, which includes optics di-
agnostics and component diagnostics.
The electronic control consists of two sepa-
rate printed circuit boards mounted on oppo-
site sides of the freezer liner just inside the
door. The board mounted on the freezer door
hinge-side of the cabinet is referred to as the
“emitter board,” and the board mounted on the
mullion side is referred to as the “receiver
board.”
When the ice maker thermostat closes and sig-
nals that ice is ready to be harvested, the emit-
ter board sends out an infrared (IR) pulse. If
the path of the pulse is unobstructed to the
receiver board, the phototransistor on the re-
ceiver board will “sense” the pulse. The con-
trol will then energize a relay, which applies
power to the ice maker, and a harvest begins.