LG LTCS20020 Refrigerator can't set temperatures

[Tollerowner]

I bought this last Summer.  The refrigerator section is fine.  The freezer temperature is messed up.

A few weeks after buying it the temperature started to rise.  On maximum cooling it was about 6F.  I called for service, but they couldn't find anyone to fix it for 3 weeks.  In that time it started working properly.  The service company said that if it was working properly they were unlikely to find a problem, and then they would have to charge me for the call if they didn't.  I canceled it.

All was fine for a year.  Then the temperature dropped to -10F, regardless of how I set it.  I figured that other than wasting energy, it wasn't doing any harm, so I tried to ignore it.  After a few days it went back to normal.  

Now, a couple weeks later, the temperature went up to 20F.  I moved the contents to a neighbor's fridge.  The temperature kept climbing and got to 37F.  Then it started cooling again.  It has been at about 6F for 2 days now.  Changing the setting doesn't change anything.

Any idea what is wrong?  Can I fix it?  Any help would be appreciated.  Well, I mean other than advice not to buy LG; I know that.

 

One interesting thing is that in a 69F room, one side is 71F and the other side is 77F.  That is rather different then the nearby freezer that is 81F on both sides.  Is that just how they are made, or is it a symptom?

 

[Vance R]

Just some standard questions.  Is the refrig on 3 prong outlet with properly voltage, polarity and ground? Have you done a reset by unplugging for at least 1 minute and reapplying power? Is there frost or ice on back wall of freezer? Next has the display been abnormal?  To check for hidden error codes push and hold the temperature adjust button - what is the pattern of the lights.

This refrig has a condenser down low in the back. They use a fan to move across the condenser so the temp difference maybe from the air flow. Which reminds me - is the condenser clean?

[Tollerowner]

3 prong outlet with everything proper.

I never deliberately shut the power off, but we have had several short power failures.

Display is normal and lights respond properly

I haven't looked at the condenser, but it started misfunctioning when it was 2 weeks old, and then was okay for a year.  Dirty condenser doesn't make much sense.
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For the last week it has slowly been going down in temperature from 6F to 0F now.  Based on past performance, it will probably just keep going down.  

 

 

[Tollerowner]

I should add that I have two thermometers, one electronic that connects by radio and one mechanical.  They agree.

[Vance R]

Next would be to check the main module for flashing led. If no flash for compressor issue it would be time to check the thermistors and drive voltage to the compressor. Take measurement when working good and then  when it is not cooling well to compare results. This will help determine if it is control or sealed system issue. 

[Tollerowner]

On 12/18/2022 at 8:45 PM, Vance R said:

Next would be to check the main module for flashing led. If no flash for compressor issue it would be time to check the thermistors and drive voltage to the compressor. Take measurement when working good and then  when it is not cooling well to compare results. This will help determine if it is control or sealed system issue. 

That sounds like a plan, but I don't know where the main module or where to test the voltage.  Are there illustrations anywhere?

A couple days ago we had a 20 second power outage.  When we got power back the temperature quickly climbed to 17F and ten back down to 0F.   Defrosting?