GE Electronic Icemaker Technical Service Manual

GE Consumer Home Services Training

TECHNICAL SERVICE GUIDE

Electronic Icemaker

Pub # 31-9063  8/00

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IMPORTANT SAFETY NOTICE

The information in this service guide is intended for use by
individuals possessing adequate backgrounds of electrical,
electronic and mechanical experience. Any attempt to repair a
major appliance may result in personal injury and property
damage. The manufacturer or seller cannot be responsible for the
interpretation of this information, nor can it assume any liability in
connection with its use.

CAUTION

To avoid personal injury, disconnect power before servicing this
product. If electrical power is required for diagnosis or test
purposes, disconnect the power immediately after performing the
necessary checks.

RECONNECT ALL GROUNDING DEVICES

If grounding wires, screws, straps, clips, nuts, or washers used
to complete a path to ground are removed for service, they must
be returned to their original position and properly fastened.

GE Consumer Home Services Training

Technician Service Guide

Copyright © 2000

All rights reserved. This service guide may not be reproduced in whole or in part
in any form without written permission from the General Electric Company.

Electronic Icemaker

Beginning in the Spring 2001, a newly
designed icemaker will be introduced in
several refrigerators. This service guide will
help you become familiar with the icemaker
and its operation.

The icemaker contains several new and
innovative features. It has an electronic
control board, an on-off switch, a seven ice
cube mold, a lever style feeler arm and a
thermistor to monitor temperature.

The control board contains two sensors
(Hall effect sensors), that are similar to an
electronic reed switch. The sensors are
activated by magnets and are used to assist
in controlling icemaker operation. One
magnet, attached to the end of the ejector
arm, allows the control board to use magnetic
sensing to determine if the motor has reached
the home position. The second magnet,
located on the ice sensing arm (feeler arm),
lets the control know whether the arm has
reached a fully extended position.

MAGNET 1

MAGNET 2

To access the
control board and
other components
within the icemaker,
lift and remove the
plastic plug at the top
of the cover. Remove
the Phillips screw
holding the cover in
place.

The control board is held in place by three
Phillips screws. All wiring is connected to the
board by plug-on terminals.

The on-off rocker switch allows the
icemaker to be turned off. When the switch
is set to on, a green LED on the right side of
the cover will light to show power is on. The
LED is also used to indicate certain icemaker
fault conditions, such as an open or shorted
thermistor, or a harvest cycle longer than 30
minutes. When a fault occurs, the LED will
blink 1/2 second on, 1/2 second off indefinitely
until the icemaker is turned off.

POWER LED

1

The feeler arm moves horizontally. A full
ice bucket will prevent the arm from moving out
to the fully extended position, stopping the next
harvest cycle until ice cubes are removed and
the arm is able to swing out completely

FEELER ARM

FULLY EXTENDED

The thermistor is mounted in the mold body,
directly behind the control housing. The
thermistor provides two functions: to measure
the ice temperature during freezing and for
water level detection during fill.

Freeze

The “Freeze” cycle is the period where
the icemaker is waiting for the cubes to freeze
solid. This period of time is based on an
algorithm programmed into the electronic
control. The control makes these calculations
once per second and takes into account the
thermistors current resistance value and the
rate of resistance change. As a result, freeze
times vary based on refrigerator control settings
and environmental conditions (door openings,
room temperature, etc.) but average
approximately 75 minutes for each drop of 7
ice cubes.

Harvest

The “Harvest” cycle will begin when the
freeze algorithm has been satisfied and the arm
is in the “out” or “fully extended” position. If the
arm is in the “in” position when harvest is to
begin, a delay of 3 minutes will be added once
the arm moves to the extended position. This
3 minute delay allows drawer type ice buckets
to be removed for up to 3 minutes without
starting a harvest. The 3 minute delay will begin
again if the arm goes back to the “in” position
anytime during the delay period. The arm is
spring loaded and will go to the out position
unless it is being held in position by an obstacle
such as an ice cube.

THERMISTOR

The normal icemaker sequence is to fill the
mold with water, wait until the water is frozen,
harvest the ice and then repeat the cycle. To
accomplish this, three cycles are programmed
in the electronic control: Freeze, Harvest and
Water Fill. The control also contains a Power­On Diagnostic Test mode, a Harvest Fix mode,
a Fault mode and a Service Diagnostic Test
mode.

SPRING

PHILLIPS

SCREW

At the start of the harvest cycle, the mold heater
will be turned on. One second later, the motor
will start. The heater will remain on until the
mold temperature is above 35.6°F (2°C) and a

2

Water Fill

minimum of 20 seconds have elasped. If

necessary, the heater will cycle with a turn on

temperature of 32°F (0°C) and a turn off

temperature of 35.6°F (2°C)

To insure the motor completes a full
revolution, the control checks to see the motor
is “not home” for at least 10 seconds and the
feeler arm is “in” for at least 10 seconds. Once
these two conditions are met and the motor
reaches home position, the harvest cycle will
be complete and the motor will turn off.

The harvest cycle consists of one
complete revolution of the ejector to sweep the
cubes from the mold and drop them into the
ice bucket. If the harvest cycle is not complete
within 7 minutes, the control will assume that a
cube is blocking the completion of a cycle and
will initiate a harvest fix mode. If the harvest
cycle is not complete within 30 minutes, the
control will assume some other problem has
occurred and will enter the fault mode.

Harvest Fix

If the harvest cycle is not complete
within 7 minutes, the control will enter a “Harvest
Fix” mode. In the harvest fix mode, the
temperature of the mold will be raised in an
attempt to melt any cubes that are jammed. The
control will turn the heater off when the
thermistor temperature reaches 68°F (20°C)
and turn it back on again at 59°F (15°C). During
this time, the motor will be cycled off for 10
seconds of every minute. If the motor reaches
the home position, a second revolution of the
ejector will occur to verify there is no more
blockage. When the second revolution is
complete, the control will enter the freeze cycle
without allowing a water fill to insure against a
double shot of water. The control will enter a
Fault Mode if a harvest cycle (including harvest
fix) is not complete within 30 minutes. Potential
causes for a harvest to take longer than 30
minutes are:

• Stuck ejector - caused by a cube that was
not cleared or a mechanical problem

• Bad heater - caused by the heater, control
board or thermal cutout (TCO)

• Bad motor - caused by motor or control
board

• Motor home position not operating - caused
by control board or loose magnet - the result
will be continuous ejector operation

• Thermistor - open or shorted

When harvest is complete, the icemaker
will enter the “Water Fill” cycle. The amount of
water entering the mold is controlled by
temperature. Before any water enters, the mold
must reach a temperature of 35.6°F (2°C). This
“prechilling” of the mold allows the thermistor
to better detect the level of the water. Water
entering the icemaker will cause the mold
temperature to change, effecting the resistance
of the thermistor.

THERMISTOR

The icemaker thermistor has a negative
coefficient. That is , an increase in temperature
will cause a decrease in resistance. The chart
below shows the most common values used
by the electronic control.

˚F ˚C

-40

35.6

39.2
50

-40
2
4

10
59 15
68 20
77

25

176 80

Once the mold has completed harvest
and cooled to 35.6°F (2°C), a first fill will be
initiated. This first fill activates the water valve
for 5.1 seconds. After this fill, there will be a 15
second delay before determining if the icemaker
is sufficiently full. If the temperature exceeds

39.2°F (4°C) after the 15 second delay, the
icemaker will end the water fill cycle and start

207K

25.37K

23.27K

18.07K

14.75K

12.11K

10K

1.67K

3

Thermistor Diagnostics

the freeze cycle. If the temperature is still below

39.2°F (4°C) after 15 seconds, the control will
assume an insufficient amount of water entered
the mold. It will then energize the water valve
again for 2.5 seconds, dela y for 15 seconds and
test again. After the second fill, if the thermistor
is still below 39.2°F (4°C), a third fill for 2.4
seconds will occur. There is a maximum of three
fills available, at which point the fill cycle will
end and the icemaker will enter the freeze cycle.
No diagnostic information will show if 3 fills were
insufficient to fill the icemaker mold. The table
below shows the possible water fill times:

First Fill 5.1 seconds
Second Fill 2.5 seconds
Third Fill 2.4 seconds

The ability of the control to fill up to three

times can compensate for low water pressure
being supplied to the icemaker.

Power On Diagnostics

When the icemaker is first connected
to power and if thermistor temperature is 50°F
(10°C) or higher, the control will perform a
Po wer On test before entering the freeze cycle.
The test consists of the following:

• Turn on the motor until it reaches home the
next time.

• Turn on the water valve for 1/2 second.

• Turn on the heater for 1/2 second.

• Verify that the feeler arm was in the “in” and
then in the “out” position.

• Verify that the motor was not in the home

position and then in the home position.

• V erify that the motor does not remain on after
being turned off.

• Proceed to the freeze cycle.

During icemaker operation, the control
continuously monitors the thermistor resistance
value. If the thermistor is open or shorted (too
high or too low in resistance), the icemaker will
enter the Fault Mode . When in the f ault mode,
the LED will flash at the rate of 1/2 second on
and 1/2 second off.

A temperature of -40°F (-40°C) will be
considered too low and a temperature of 176°F
(80°C) is too high for normal operation to
continue. When out of range, a fault mode will
be entered, yet the thermistor will continue to
be tested. If the reading should later f all within
the valid range, the f ault mode will end and the
icemaker will enter the freeze cycle. If the motor
is not home, the control will restart the harvest
cycle, follow ed b y the freez e cycle , b ut b ypass
the water fill.

Service Diagnostics

During the first 15 seconds that power
is first applied to the icemaker, the Service
Diagnostic Test mode may be entered. The
service mode is entered by pushing the feeler
arm from the “out” position to the “in” position
and back again 3 times
15 seconds.

3 TIMES WITHIN 15 SECONDS

and only 3 times

within

Note: The power on test will only add 1/2 second
of water, which will not overflow the mold with
a normal fill, but may cause a small cube when
the refrigerator is first started.
If the temperature is below 50°F (10°C), the
control will power up normally. If in the home
position, the control will enter the freeze cycle.
If the motor is not home, the control will enter
the harvest cycle but bypass water fill to avoid
overfilling the mold.

Note: If the icemaker has already started a
harvest cycle and the arm is moving, it may be
impossible to properly move the arm and enter
the service mode without allowing it to reset
and powering up again.

The service diagnostic mode consists
of a harvest cycle followed by a water fill. The
harvest cycle is entered immediately , regardless
of icemaker temperature or arm position.

4

While in the harvest cycle in the service mode,
the heater will remain on for a minimum of 20
seconds. The water fill cycle will initiate the
first fill (5.1 seconds) without waiting for the mold
to “prechill”. Only one water fill occurs dur ing
the service mode, whether the thermistor has
reached 39.2°F (4°C) or not. The icemak er will
exit the service diagnostic test on its own and
enter the normal freeze cycle.

NOTE: When replacing an icemak er, the P ower
On test will probably occur since the mold
temperature will be above 50°F (10°C). While
in the power on test, the Service Diagnostic test
can be initiated and will override the power on
test mode.

FREEZE

CYCLE

Wait

until frozen

(

minimum 30 minutes)

(usually takes about 60 minutes)

NORMAL OPERATION

(EJECTOR STARTING AT HOME POSITION)

MOTOR ON

HEATER ON

HEATER ON

until 35.6˚F (2˚C)

(minimum 20 seconds)

MOTOR ON

3

MINUTES

PRECHILL

CYCLE

About

10 MINS.

Less than

35.6˚F (2˚C)

V
A

O

L

N

V
E

5.1

secs.

5

Failure

Magnet Failure

Control Board Failure

Stalled Motor

Winding Failure

Motor Failure

Wrong Connection

Bent/Broken Shaft

Loose Lead

Loose/Broken Gear

Heater Element

Ground

Heater Failure

TCO Failure

Open Circuit

Jammed Cube

Loose Lead

Water Valve Failure

Loose Lead

Bad Switch

Thermistor Failure

Control Board Failure

Ejector Not Home

Water Supply Shut Off

Control Board Failure

Bad Thermistor

ICEMAKER TROUBLESHOOTING

No LED

LED

Flashing

No Fill

No Ice

Thermistor Failure

Stalled Motor

Bucket Full

Magnet Failure

Feeler Arm Stuck

No Harvest

Control Board Failure

(dispenser / icemaker reversed)

Improper Water Valve Connection

Water Valve Failure

Control Board Failure

Thermistor Failure

(due to extremely cold inlet water)

Harvest Too Early

Water

Thermistor Not Detecting Fill

Overflow

Control Board Failure

6

GROUND

LINE

NEUTRAL

WATER
VALVE

115 VOLTS AC. 60HZ

GREEN WITH YELLOW STRIPE

BROWN

POWER
SWITCH

PCB ASSEMBLY

RED

ORANGE

WHITE

ORANGE

BLACK

T.C.O.

HEATER

ORANGE

MOTOR

WHITE

THERMISTOR

MOLD BODY

LD1

BLACK

THERMISTOR

TERMINALS

C14

MOTOR

ORANGE

ICEMAKER

BLACK

U1

X1

TCO VALVE N

RED

WHITE

U2

HEATER

ORANGE

BLACK

DB1

C1

C13

C12

MOV1

L1

BROWN

7

8

QUESTIONS

1. What activates the two Hall Effect Sensors on the control board?
A. Ejector arm
B. Magnets
C. Feeler arm position
D. Water level

2. What type of mode is indicated by the power LED flashing off & on?
A. Harvest mode
B. Power on mode
C. Fault mode
D. Control mode

3. The thermistor provides two functions: to measure the __________ temperature during
freezing and for ___________ level detection during fill.
A. Thermistor / Water
B. Ejector / Ice
C. Heater / Mold
D. Ice / Water

4. The three cycles that are programmed into the electronic control are:
A. Freeze, Harvest & Water Fill
B. Power on, Thermistor & Service
C. Power on, Harvest Fix & Three Fills
D. Normal Operation, Diagnostics & Harvest Fix

5. During the freeze cycle, the algorithm programmed into the control takes several items into
consideration before entering the harvest mode. However, on an average, how often does the
icemaker cycle and drop its seven cubes?
A. 120 Minutes
B. 90 Minutes
C. 75 Minutes
D. 60 Minutes

6. If the harvest cycle is not complete within 7 minutes, the control will assume that a cube is
blocking the completion of a cycle and will initiate a _____________?
A. Power on diagnostics
B. Harvest fix mode
C. Water fill
D. Fault Mode

7. If the harvest cycle is not complete within 30 minutes, the control will assume some other
problem has occurred and will enter a ____________?
A. Power on diagnostics
B. Harvest fix mode
C. Water fill
D. Fault Mode

8. The amount of water enter the mold during the water fill mode is controlled by _________?
A. Temperature
B. Pressure
C. Time
D. Hall Effect

9

9. The ability of the control to fill up to 3 times can compensate for ___________?
A. Multiple ejections
B. Service diagnostics
C. Low water pressure
D. Extremely cold freezer

10. When the icemaker is first connected to power and if thermistor temperature is 50° F or
higher, the control will perform a _________________ before entering the freeze cycle.
A. Harvest fix
B. Series of fluctuations
C. Power on test
D. Fault test

11. During icemaker operation, the control continuously monitors the thermistor’s __________?
A. Resistance
B. Temperature
C. Mode
D. Diagnostics

12. If the thermistor is open or shor ted, the icemaker will enter a ______________?
A. Harvest mode
B. Period of inactivity
C. Fault mode
D. Third water fill

13. The diagnostic service mode is entered by pushing the feeler arm from the “out” position to
the “in” position and back _______ times during the first 15 seconds after applying power to
the unit.
A. 2
B. 3
C. 4
D. 5

10