Whirlpool 4322658A Podręcznik - Strona 13

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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.

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.

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.

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