GE Electronic Ice Maker #31-9063

Electronic Icemaker

GE Consumer Home Services Training

TECHNICAL SERVICE GUIDE

Pub # 31-9063 8/00

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.

!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.

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 TrainingTechnician 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.

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POWER LED

MAGNET 1MAGNET 2

The control board contains two sensors(Hall effect sensors), that are similar to anelectronic reed switch. The sensors areactivated by magnets and are used to assistin controlling icemaker operation. Onemagnet, attached to the end of the ejectorarm, allows the control board to use magneticsensing to determine if the motor has reachedthe home position. The second magnet,located on the ice sensing arm (feeler arm),lets the control know whether the arm hasreached a fully extended position.

The on-off rocker switch allows theicemaker to be turned off. When the switchis set to on, a green LED on the right side ofthe cover will light to show power is on. TheLED is also used to indicate certain icemakerfault conditions, such as an open or shortedthermistor, or a harvest cycle longer than 30minutes. When a fault occurs, the LED willblink 1/2 second on, 1/2 second off indefinitelyuntil the icemaker is turned off.

Electronic Icemaker

Beginning in the Spring 2001, a newlydesigned icemaker will be introduced inseveral refrigerators. This service guide willhelp you become familiar with the icemakerand its operation.

The icemaker contains several new andinnovative features. It has an electroniccontrol board, an on-off switch, a seven icecube mold, a lever style feeler arm and athermistor to monitor temperature.

To access thecontrol board andother componentswithin the icemaker,lift and remove theplastic plug at the topof the cover. Removethe Phillips screwholding the cover inplace.

The control board is held in place by threePhillips screws. All wiring is connected to theboard by plug-on terminals.

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FULLY EXTENDEDFEELER ARM

THERMISTOR

SPRING

PHILLIPSSCREW

Freeze

The “Freeze” cycle is the period wherethe icemaker is waiting for the cubes to freezesolid. This period of time is based on analgorithm programmed into the electroniccontrol. The control makes these calculationsonce per second and takes into account thethermistors current resistance value and therate of resistance change. As a result, freezetimes vary based on refrigerator control settingsand environmental conditions (door openings,room temperature, etc.) but averageapproximately 75 minutes for each drop of 7ice cubes.

Harvest

The “Harvest” cycle will begin when thefreeze algorithm has been satisfied and the armis in the “out” or “fully extended” position. If thearm is in the “in” position when harvest is tobegin, a delay of 3 minutes will be added oncethe arm moves to the extended position. This3 minute delay allows drawer type ice bucketsto be removed for up to 3 minutes withoutstarting a harvest. The 3 minute delay will beginagain if the arm goes back to the “in” positionanytime during the delay period. The arm isspring loaded and will go to the out positionunless it is being held in position by an obstaclesuch as an ice cube.

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

The feeler arm moves horizontally. A fullice bucket will prevent the arm from moving outto the fully extended position, stopping the nextharvest cycle until ice cubes are removed andthe arm is able to swing out completely

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

The normal icemaker sequence is to fill themold with water, wait until the water is frozen,harvest the ice and then repeat the cycle. Toaccomplish this, three cycles are programmedin the electronic control: Freeze, Harvest andWater Fill. The control also contains a Power-On Diagnostic Test mode, a Harvest Fix mode,a Fault mode and a Service Diagnostic Testmode.

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minimum of 20 seconds have elasped. Ifnecessary, the heater will cycle with a turn ontemperature of 32°F (0°C) and a turn offtemperature of 35.6°F (2°C)

To insure the motor completes a fullrevolution, the control checks to see the motoris “not home” for at least 10 seconds and thefeeler arm is “in” for at least 10 seconds. Oncethese two conditions are met and the motorreaches home position, the harvest cycle willbe complete and the motor will turn off.

The harvest cycle consists of onecomplete revolution of the ejector to sweep thecubes from the mold and drop them into theice bucket. If the harvest cycle is not completewithin 7 minutes, the control will assume that acube is blocking the completion of a cycle andwill initiate a harvest fix mode. If the harvestcycle is not complete within 30 minutes, thecontrol will assume some other problem hasoccurred and will enter the fault mode.

Harvest Fix

If the harvest cycle is not completewithin 7 minutes, the control will enter a “HarvestFix” mode. In the harvest fix mode, thetemperature of the mold will be raised in anattempt to melt any cubes that are jammed. Thecontrol will turn the heater off when thethermistor temperature reaches 68°F (20°C)and turn it back on again at 59°F (15°C). Duringthis time, the motor will be cycled off for 10seconds of every minute. If the motor reachesthe home position, a second revolution of theejector will occur to verify there is no moreblockage. When the second revolution iscomplete, the control will enter the freeze cyclewithout allowing a water fill to insure against adouble shot of water. The control will enter aFault Mode if a harvest cycle (including harvestfix) is not complete within 30 minutes. Potentialcauses for a harvest to take longer than 30minutes are:• Stuck ejector - caused by a cube that wasnot cleared or a mechanical problem• Bad heater - caused by the heater, controlboard or thermal cutout (TCO)• Bad motor - caused by motor or controlboard• Motor home position not operating - causedby control board or loose magnet - the resultwill be continuous ejector operation• Thermistor - open or shorted

THERMISTOR

˚F ˚C

-40 -40

35.6 2

39.2 450 10

59 15

68 20

77 25 10K

176 80

207K

25.37K

23.27K

18.07K

14.75K

12.11K

1.67K

Water Fill

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

The icemaker thermistor has a negativecoefficient. That is, an increase in temperaturewill cause a decrease in resistance. The chartbelow shows the most common values usedby the electronic control.

Once the mold has completed harvestand cooled to 35.6°F (2°C), a first fill will beinitiated. This first fill activates the water valvefor 5.1 seconds. After this fill, there will be a 15second delay before determining if the icemakeris sufficiently full. If the temperature exceeds39.2°F (4°C) after the 15 second delay, theicemaker will end the water fill cycle and start

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3 TIMES WITHIN 15 SECONDS

Thermistor Diagnostics

During icemaker operation, the controlcontinuously monitors the thermistor resistancevalue. If the thermistor is open or shorted (toohigh or too low in resistance), the icemaker willenter the Fault Mode. When in the fault mode,the LED will flash at the rate of 1/2 second onand 1/2 second off.

A temperature of -40°F (-40°C) will beconsidered too low and a temperature of 176°F(80°C) is too high for normal operation tocontinue. When out of range, a fault mode willbe entered, yet the thermistor will continue tobe tested. If the reading should later fall withinthe valid range, the fault mode will end and theicemaker will enter the freeze cycle. If the motoris not home, the control will restart the harvestcycle, followed by the freeze cycle, but bypassthe water fill.

Service Diagnostics

During the first 15 seconds that poweris first applied to the icemaker, the ServiceDiagnostic Test mode may be entered. Theservice mode is entered by pushing the feelerarm from the “out” position to the “in” positionand back again 3 times and only 3 times within15 seconds.

Note: If the icemaker has already started aharvest cycle and the arm is moving, it may beimpossible to properly move the arm and enterthe service mode without allowing it to resetand powering up again.

The service diagnostic mode consistsof a harvest cycle followed by a water fill. Theharvest cycle is entered immediately, regardlessof icemaker temperature or arm position.

the freeze cycle. If the temperature is still below39.2°F (4°C) after 15 seconds, the control willassume an insufficient amount of water enteredthe mold. It will then energize the water valveagain for 2.5 seconds, delay for 15 seconds andtest again. After the second fill, if the thermistoris still below 39.2°F (4°C), a third fill for 2.4seconds will occur. There is a maximum of threefills available, at which point the fill cycle willend and the icemaker will enter the freeze cycle.No diagnostic information will show if 3 fills wereinsufficient to fill the icemaker mold. The tablebelow shows the possible water fill times:

First Fill 5.1 seconds

Second Fill 2.5 secondsThird Fill 2.4 seconds

The ability of the control to fill up to threetimes can compensate for low water pressurebeing supplied to the icemaker.

Power On Diagnostics

When the icemaker is first connectedto power and if thermistor temperature is 50°F(10°C) or higher, the control will perform aPower On test before entering the freeze cycle.The test consists of the following:• Turn on the motor until it reaches home thenext 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” andthen in the “out” position.• Verify that the motor was not in the homeposition and then in the home position.• Verify that the motor does not remain on afterbeing turned off.• Proceed to the freeze cycle.

Note: The power on test will only add 1/2 secondof water, which will not overflow the mold witha normal fill, but may cause a small cube whenthe refrigerator is first started.If the temperature is below 50°F (10°C), thecontrol will power up normally. If in the homeposition, the control will enter the freeze cycle.If the motor is not home, the control will enterthe harvest cycle but bypass water fill to avoidoverfilling the mold.

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While in the harvest cycle in the service mode,the heater will remain on for a minimum of 20seconds. The water fill cycle will initiate thefirst fill (5.1 seconds) without waiting for the moldto “prechill”. Only one water fill occurs duringthe service mode, whether the thermistor hasreached 39.2°F (4°C) or not. The icemaker willexit the service diagnostic test on its own andenter the normal freeze cycle.

NOTE: When replacing an icemaker, the PowerOn test will probably occur since the moldtemperature will be above 50°F (10°C). Whilein the power on test, the Service Diagnostic testcan be initiated and will override the power ontest mode.

MOTOR ONFREEZECYCLE

PRECHILLCYCLE

ON

VALVE

MOTOR ON3 MINUTES

Waituntil frozen

(minimum 30 minutes)

About10 MINS.Less than

35.6˚F (2˚C)

5.1secs.

NORMAL OPERATION(EJECTOR STARTING AT HOME POSITION)

HEATER ON

(usually takes about 60 minutes)

HEATER ON until 35.6˚F (2˚C)

(minimum 20 seconds)

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115 VOLTS AC. 60HZ

PCB ASSEMBLY THERMISTOR

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QUESTIONS

1. What activates the two Hall Effect Sensors on the control board?A. Ejector armB. MagnetsC. Feeler arm positionD. Water level

2. What type of mode is indicated by the power LED flashing off & on?A. Harvest modeB. Power on modeC. Fault modeD. Control mode

3. The thermistor provides two functions: to measure the __________ temperature duringfreezing and for ___________ level detection during fill.A. Thermistor / WaterB. Ejector / IceC. Heater / MoldD. Ice / Water

4. The three cycles that are programmed into the electronic control are:A. Freeze, Harvest & Water FillB. Power on, Thermistor & ServiceC. Power on, Harvest Fix & Three FillsD. Normal Operation, Diagnostics & Harvest Fix

5. During the freeze cycle, the algorithm programmed into the control takes several items intoconsideration before entering the harvest mode. However, on an average, how often does theicemaker cycle and drop its seven cubes?A. 120 MinutesB. 90 MinutesC. 75 MinutesD. 60 Minutes

6. If the harvest cycle is not complete within 7 minutes, the control will assume that a cube isblocking the completion of a cycle and will initiate a _____________?A. Power on diagnosticsB. Harvest fix modeC. Water fillD. Fault Mode

7. If the harvest cycle is not complete within 30 minutes, the control will assume some otherproblem has occurred and will enter a ____________?A. Power on diagnosticsB. Harvest fix modeC. Water fillD. Fault Mode

8. The amount of water enter the mold during the water fill mode is controlled by _________?A. TemperatureB. PressureC. TimeD. Hall Effect

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9. The ability of the control to fill up to 3 times can compensate for ___________?A. Multiple ejectionsB. Service diagnosticsC. Low water pressureD. Extremely cold freezer

10. When the icemaker is first connected to power and if thermistor temperature is 50° F orhigher, the control will perform a _________________ before entering the freeze cycle.A. Harvest fixB. Series of fluctuationsC. Power on testD. Fault test

11. During icemaker operation, the control continuously monitors the thermistor’s __________?A. ResistanceB. TemperatureC. ModeD. Diagnostics

12. If the thermistor is open or shorted, the icemaker will enter a ______________?A. Harvest modeB. Period of inactivityC. Fault modeD. Third water fill

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