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Author Topic: LG Fridge or Freezer not cooling, compressor and valve changed  (Read 1043 times)

Offline Johnn

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LG Fridge or Freezer not cooling, compressor and valve changed
« on: February 01, 2021, 11:37:40 AM »

Seems to be a knowledgeable group...hopefully I may get some help.
History, LG LFX31945ST compressor running fridge and freezer not cooling. I called LG support indicating that I thought the compressor failed after my research. Fridge out of warranty, compressor warranty. They said they would send a tech out but I would have to pay for labor...okay. Following week tech comes to change compressor but encourages me to also change three way valve. Said he recommended I do as they fail and it would be another seal system cost to do it in the future. I am not a refrigerator tech...but I am a technician otherwise. He changed compressor and valve, told me to give it 24hours and left. Next day fridge cold freezer warm. Called them back, they said following week a tech would come and check it. A different tech came. I told him about the valve, which is what I was now suspecting. He said no, it was a blockage and they could not fix it and LG would refund me or give me a replacement...yeh right. After talking with LG, I would get less than two hundred dollars for my more than three thousand $ fridge...as I paid for labor and three way valve.
Still suspecting the valve, I did more research and figured out how it works, also about the home position, test, and feeling for rotation. As an electronic tech I know about stepper motor. So I removed the coil drive and apply a magnet to rotate the rotor. I can now get the freezer and fridge evaporator to frost, the fridge alone or the freezer alone to frost. So I cannot believe it is a blockage. I looked at the part # for the valve installed AJU74892401 more research said the part number should be AJU34510512 which screws on the frame. I do not know what was on it before. I called LG parts and asked about these two parts, after awhile told me either would work. So now I can't claim that it is the wrong part. Any help would be appreciated.

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #1 on: February 03, 2021, 05:32:01 PM »
How did you turn it with a magnet I would like to see the method.
Does it vibrate when you press the test button on the mainboard?
Do you know if they put your old coil on a new valve body because that valve is sold without the coil.
There was a bulletin about the older valves were not the same as the newer valves, old ones were metal coil newer has black plastic over the coil and you cannot interchange them they will turn the wrong way when energized. Wonder if that is what happened.
How old is the fridge?

Offline Johnn

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #2 on: February 03, 2021, 11:48:04 PM »
Thanks for the reply Houptee. From the diagram the rotor is a permanent magnet. So if you apply another magnet it will attract at opposite poles. Just keep the magnet in the same orientation and rotate it around the metal housing. You can turn it about 2 and a 1/8 turns then you will feel the magnet resisting.
Yes it does vibrate and feels like four pulses at times.
The one they put on has a black plastic cover over the coil. That may very well be the problem. Why would LG parts tell me the two part number would work...you say there was a bulletin about this. The LG tech should have known this.
The fridge is 7 years old.
I do appreciate your information.

Offline shillion

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #3 on: February 04, 2021, 05:02:46 AM »
Hello Houptee,I am Shillion,I found this interesting.The original LG tech thought the system was plugged up.But it was not.I would like to find out how the sequence of the fridge start from cold .Where can I find this info?

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #4 on: February 04, 2021, 07:36:01 AM »
This is the bulletin about the 3 way valve and mainboard compatibility issue.

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #5 on: February 04, 2021, 07:49:43 AM »
Did they replace the upper evaporator coil or pull the cover off inside fridge section and check anything?
These models had history of micro pinhole leaks in upper evaporator which will appear as black oily spots all over the white plastic and on the evaporator.
The leaks allow air to draw into the system and chemically react with the POE oil which absorbs moisture from the air. Formation of acids and waxy gel clogs up the capillary tubes.
Then another issue on these is where the capillary tube enters the evaporator the factory put a tiny crimp in the tube to cut down on the gurgling noise. But this crimp makes a restriction in the already tiny capillary tube and that is where the debris gets caught and clogs the system.
And other problems are when the air enters the system the compressor overheats and spits out the oil into the condenser coil clogging it up with black sludge and oil.
Usually techs blow out the system with 200 psi nitrogen to try and get the black stuff and oil out before installing new compressor and filter drier.
Sometimes its ok bit other times its a lost cause and stops cooling again then they just say its non repairable.

Offline Johnn

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #6 on: February 04, 2021, 07:36:46 PM »
Thanks Houptee for the information.
No they did not take off the cover over the evaporator in the fridge.
The second LG tech that said there was a blockage did pull off the cover for the Freezer evaporator...when he did not see it freezing/frosting up he said it was blocked and the unit could not be fixed.
Why is it the when I move the threeway valve to different positions the Freezer frost another position the Fridge frost. Wouldn't the blockage prevent one or both of them from working?
This is what the valve he put on looks like.

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #7 on: February 04, 2021, 08:40:08 PM »
Yes it is strange that it works when you force it to change position. When you press the test button on mainboard 1 time it should move valve to home position (both evaps fed with gas). Then you can unplug fridge while in test mode 1 and look down near the water inlet valve there is a harness connector that goes to the 3 way valve. Unplug the harness there (its easier than trying to fit your hand in to unplug at the 3 way valve). Then power up the fridge again and let it run for 24 hrs see if both boxes get cold. Basically you will be running it forced to cool both evaporators all the time with the valve unplugged in home position. Then if it cools you know the 3 way is the problem or possibly the mainboard is not controlling the 3 way properly.
Some time the tech accidentally solders the tiny tube closed when brazing in the 3 way valve and its plugged shut but you said it cools when you use magnet but did both evaps cool or just one?
Other possibility is he mixed up the tubes at the 3 way valve and they go to the wrong evap.

Offline Johnn

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #8 on: February 04, 2021, 11:18:04 PM »
No the test button moves it to the fridge section. Only when I move it with the magnet will it frost both evaporators.

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #9 on: February 06, 2021, 08:31:16 AM »
Only thing I can think is the mainboard is not matched to the 3 way valve per that bulletin I posted.
Did you check the numbers on your mainboard and compare to the bulletin for the 2 valves?
Or if you had a grey valve head you could try that instead of the black head see if it works.
Look on ebay maybe you can find used one cheap.

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #10 on: February 06, 2021, 09:04:57 AM »
Hello Houptee,I am Shillion,I found this interesting.The original LG tech thought the system was plugged up.But it was not.I would like to find out how the sequence of the fridge start from cold .Where can I find this info?

What model are you working on do you have the service manual?

Offline houptee

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Offline Johnn

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #12 on: February 06, 2021, 09:49:42 AM »
Only thing I can think is the mainboard is not matched to the 3 way valve per that bulletin I posted.
Did you check the numbers on your mainboard and compare to the bulletin for the 2 valves?
Or if you had a grey valve head you could try that instead of the black head see if it works.
Look on ebay maybe you can find used one cheap.

The LG tech did not change the wire harness...no way...the one in it now has dust on it,.
Looking close at the picture online with that 3way valve the wire connections are different. He did update the firmware on the motherboard. Not sure if that would also have something to do with the 3way valve and not only the compressor.
I will try and pin out the wires. The online picture shows 5 wires the one I have is 6 wires. Guess mine has two center tap coil wires.
Yes I did check the mainboard and my board would not be compatible with the other valve shown.  But I can't figure why LG parts would tell me that AJU74892401 and AJU34510512 are compatible and will work.

Offline Johnn

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Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #14 on: February 06, 2021, 02:23:25 PM »
Make sure the actuator head is on the valve in correct orientation. I think it has a small tab on the bullet that has to fit into a notch under the actuator. Maybe its on 180 deg out of wack? I never took the actuator off one but I know they used to sell only the valve part without the actuator on it. Wonder if he used the complete valve assy with new actuator or just the bullet valve part and re-used your actuator and put it on wrong.

Offline Johnn

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #15 on: February 06, 2021, 06:16:31 PM »
He put on the whole unit, I can tell it is new. The wires that connects to it then go around the condensor to where the water line is was not changed. The part comes with it as you can see in the picture of the part I sent earlier.
I have seen the one you are talking about online but mine is not keyed.

Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #16 on: February 09, 2021, 11:15:55 PM »
Wonder if that cable harness is different and since he left the old one on it might be wired differently that the harness that came with the new valve.
He probably threw it away!

Offline Johnn

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #17 on: February 10, 2021, 07:24:40 AM »
Yes...from the pictures online it is different.
I have tried reconnecting it according to what I see online. I get a different position but it still doesn't work.
I think at this point I need to change the threeway valve to the one recommended for this unit. Just can't justify spending the money for someone to come in and do it.


Offline houptee

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Re: LG Fridge or Freezer not cooling, compressor and valve changed
« Reply #18 on: February 10, 2021, 10:35:28 AM »
That model has a history of problems the yoder tube rusts around the doors and gets pinhole leaks and so does the evaporator coil in the upper box the aluminum gets pinholes as well as the epoxy joint where they joined copper to aluminum tubing. Also heard the condenser coil which is steel painted black rusts out from sitting in the water tray by the compressor.

There is a nice french door at Lowes made by Hisense for 1300 and Best Buy sells same fridge under their house brand Insignia for around the same price.

https://www.lowes.com/pd/Hisense-26-6-cu-ft-French-Door-Refrigerator-with-Ice-Maker-Fingerprint-Resistant-Stainless-Steel-ENERGY-STAR/1003213836

https://www.bestbuy.com/site/insignia-26-6-cu-ft-french-door-refrigerator-stainless-steel/6168626.p?skuId=6168626