GE side-by-side frezzer warm, wall frost build-up

[shenjiming]

I have a GE side-by-side GSS25KGMWW starting to warm up in the freezer two weeks ago. Frost also seen built up on the back wall of freezer. Temp is around 34F. It was back to normal once but became worse after a few days.

I suspect the defrost system issue after researching here. Questions for experts:

1. Is there any way I can test on the defrost heater by a multimeter (test resistance, I assume) without pull out my unit and access the main board? IOW, is there any metal tips that I can test and read an om value to determine it is a good or bad one?

2. Is the service manual 31-9072 found in this forum applicable to this GE model?

3. Where to buy a "jump wire" to jump the main board circuit pins? Is there a reference model or picture (maybe ebay??) so that I can bring to Radioshack, or order online with?

Thanks for your help!

[Repair-man]

Yes, the manual pertains to the PSS and GSS models, so use it to test the defrost system.

No, we do not put jumper wires on the back board or anywhere else!

The manual gives you the values of the defrost heater and thermostat, and you can check their  continuity from the rear board or by removing the freezer cover and finding the heater manually and checking for continuity. It will be  buried under a ton of frost most likely, so using the manual will help you get to the correct area on the board to check. It will also show you  how to do a diagnostic from the control panel using the digital pads.

[shenjiming]

Thank you, repair-man. It is good to hear I do not have to pull the unit out in the first step troubleshooting. I just need clarification of the service manual page 52 flow chart:

Carefully unplug J9 blue connector from
main board. Measure between blue wire on
connector and neutral orange wire on main
board J7. Is there approximately 27Ω?

Is this NOT on the main control board, which is on the rear side of the refrigerator? Or I can do an equivalent on the defrost heater itself?

Also the next step:

Check for 120 VAC from
neutral orange wire J7 to
defrost terminal J9 on main
board.
Is 120 VAC present?

I assume I need a jump wire for this test, right? This was the question I referred to in the first post. I hope I can resolve the problem by first step (test the defrost heater continuity and resistance of the defrost thermstat)

Let me know if I misunderstand. Thank u again.

[Repair-man]

No jumper wires!  I say again...

When it tells you to measure voltage between 2 places, it just means to place one meter led on the blue wire, the other lead on the orange wire, etc. Your meter leads are the jumper, since you are trying to measure voltages.

I recommend that you do the tests from the back of the unit as described in the manual. This will rule out the board or the heater circuit as the problem.  Yes, you can always do it the lazy way and go in from the font of the freezer to check the heater and defrost terminator for continuity, but this will not tell you if the board in back is bad. That's why we do it mainly from the back.

The service test mode can be programmed in front to start a defrost cycle. The manual shows you how. This is only helpful if you have an amp meter to see the current draw as the heater circuit is energized. The board tests in back will be the most productive. Sorry I don't have time to tech you the steps, but if the manual is not clear to you, then you should call in a pro.

[shenjiming]

I tried to run self diagnostics illustrated in PUB # 21-9072 by pressing and holding all four temp adjustment buttons for 3 seconds. Nothing happened.  Do all GSS models have this self diagnostics functionality? If so, what was wrong with my handling of this?

Thanks!

[shenjiming]

Ok. I did a clean-up today. All the evaporator coil are iced heavily. so I used hair drier to melt them. I also did the following:

1. remove the defrost heater and test the continuity. I got 23 ohm. So I assume it is good though it has darkened inside (we have  it for more than 5 years)

2. I can see the defrost thermostate and evaporator thermistor. But I cannot find a terminal to remove them to test resistance. Their wiring basically extended to other part of the freezer as a whole. I even removed the ice maker and housing of the evaporator fan. What I can see are wires going here and there but no terminator for me to pull out for replacement or test

3. I also access the control board and performed the test in the service manual. I tested the resistance between the blue wire on J9 and orange wire (neutual) on J7. I got 23ohm as well. Then I connected the power, I can hear the compressor is humming. Then I tested blue wire on J9 and orange wire on J7 for AC voltage. I got zero. I also tested the "compressor" wire on J9 and orange on J7, I got 120V.

4. I went back to freezer and removed the defrost heater. I tested the voltage between the two open terminals (connecting the heater). I still got zero reading. while I am testing, I can hear the evaporator fan is working fine and frost started to show up immediately.

Now my questions:

1. Based on the manual, this looks like either a wiring problem or thermistor. I wonder if the thermistor malfunctions, will I get zero reading on the blue/J9 to orage/J7 on the board, and zero voltage on both terminals of defrost heater? In other words, is this evaporator thermistor controlling the voltage to the defroster heater? Can some one confirm this to me?

2. Any easy way to test the evaporator thermistor? I found the self diag function (press all term control buttons and hold for 3 sec.) did not work on this refrigerator.  So if there is a way to test it other than self diag

3. I still do not know how to change the evap thermistor since its wire extends to some places I cannot reach at all (so does the defroster thermostat). If I buy a new one, do I just cut the wires and slice them and twist them together to get connectivity and replacement? Is this low voltage or high voltage?

4. My thermistor is a bullet (round head) one. Is this kind of GE thermistor having some higher failure rate in the history?

5. Do I have to replace the heater and defrost thermostat if I replace the evap thermistor?

Thank you!

[JWWebster]

Do you have a picture of that thermistor?

[shenjiming]

yes, here it is. The white bullet shaped thing is it (it has a snap attached to the evaporator tube)

http://picasaweb.google.com/shenjiming/GE#5326196298026141778

Wonder what is the way to replace it? Do I just cut the wires and attach the new one with orange wire nuts?

Same way to replace the defrost thermostat with orange/pink wires showing in that picture?

If I read 23ohm on between the J9/Blue and J7/orange, I suppose the defrost thermostat is good/close?

Really confused. am I having a bad wiring at certain point?

[JWWebster]

You should not get a reading on the terminator if it is warm.

[shenjiming]

Hi, JWWebster,

I might have some misunderstanding of your reply:

"You should not get a reading on the terminator if it is warm."

Do you mean:

1. I should not test the terminator (I assume J9 and J7/Orange voltage) when it is warm.


Or

2. I would not get any voltage reading (zero) when it is warm.

I cannot understand when the resistance is so low (multimeter uses DC power) while the AC voltage is zero. There must be something disconnected the AC power on one end (I know orange line is the neutual one) when it is powered on. I assume it is thermistor?

so when it is cold, I need to test the voltage and resistance again? Or just the voltage?

thanks,

[JWWebster]

Well dig, the terminator's job is to kill power to that heater when the temp is sufficient to melt frost from the coils(around 50F) thus keeping the evaporator from forming ice. If you is getting any kinda reading from that dude while it is warm then I would say that ain't a good thang.