Erratic cooling fridge and freezer, what is going on?

[BaconCentric]

Hi,

I have a Samsung fridge, circa 2008, counter depth, french door config, with icemaker / water dispenser and bottom freezer.  I'm not at home at the moment to find the model number but if needed I will get it and posted here.

A few days ago I noticed water on the floor in front of the refrigerator and it turns out it came from the ice dispenser because the ice had melted because the refrigerator is not cooling sufficiently.

It is in an enclosure with about 1 in of space on each side and 3 in of space behind, 6 in of space above.  There have not been any power interruptions.

I moved all of the food out into the garage which is in the low 50s right now, and ordered some online remote thermometers.

I disconnected the breaker and let the freezer and refrigerator warm up to room temperature for 24 hours just in case there was icing somewhere blocking the airflow. Then I reconnected it and let it cool down for a day.

Below is what I'm seeing now both in the freezer (first image) and the refrigerator (second image) over the last 24 hours.  Both freezer and refrigerator are still empty.  I have not been opening the doors for either, so the temperature fluctuations shown in the images are just whatever the cooling system is doing on its own.

Can anyone postulate a theory of what is going on?

[appl.tech.29501]

Pull unit out and check condenser and fan. Common for that fan to go bad on that Era fridge. Need model# if that's not you're problem. 

Edited October 30, 2023 by appl.tech.29501

[BaconCentric]

Do you think this might be contributing to the problem?

 

Also, model # is RFG237AARS

 

 

[appl.tech.29501]

With the clearances you posted, it's not dirty enough to cause those temp swings.

I would check thermistors

[BaconCentric]

I cleaned dust from condenser for good measure.

Upon power up condenser fan runs but not compressor.  But after what seemed like 10 minutes compressor does kick on and runs continuous (fridge started at room temp).  Found service manual which mentions 7 minute compressor start delay so that explains that.

 

FYI compressor appears to be the inverter type because the control board on the back of the fridge has a separate smaller board and one of the components on it has a sticker that says inverter.

Condensor coils are warm to touch.  Not enough to burn hand but quite warm.

Service manual indicates a self diagnostic for sensors (hold down two buttons on front display for 8 seconds).  I ran this but it indicates no sensor faults.

My next theory is if a temp sensor is electrically fine but physically came loose from evap, etc.  I seem to remember having the guts of this fridge apart once many years ago and noticing that there was a sensor that was mounted directly to the evaporator coil.  I don't remember if it was the fridge evaporator or the freezer one.  Could that explain the temperature fluctuations? Is it worth ripping all the interior panels off to check?

[BaconCentric]

So after cleaning the condensor it's been running 24 hrs now with nothing in it.

The fridge section has been fairly consistent between 34 and 43 F. 

Unfortunately the freezer section has still been erratic.  For about 12 hrs it was at or below about 10 F.  But then the freezer went from 10 F up to 45 F and then back down to -18 F over about an 8 hr period.  See the attached pic.

 

So on a whim, I repeated the sensor self-diagnostic procedure that I tried immediately after powering up.  When the fridge first powered up the self-diagnostic indicated no faults. But this time it did indicate a fault:

"F-DEF.-Heater error.  Defrost system in FZ compartment errors"

Looks like next step is access the controller and test this sensor for open or short.

 

[BaconCentric]

Measured resistance of defrost heater.. it jumped around a lot .. 60 Ohms, 80 Ohms, zero, infinite.  I tried to hold the probes very still so I don't think it was me intermittently connecting the ohm meter.. rather strange.  I guess taking the freezer interior covers off is the next step.

[BaconCentric]

Gotta love it when your refrigerator's service manual contains notes to the tech writer instead of actual content...

 

[BaconCentric]

So I checked a few more things, follow the diagnostic flow chart posted here on this site, also the various troubleshooting steps in the service manual.

One thing I checked was the inverter compressor windings, all three are the correct resistance and within 1/10 ohm of each other. So that checks out.

The inverter board has 110 volt supplied. I put an AC current meter around one of the three power leads to the compressor and when fridge is initially powered up it does briefly show about one amp. It's probably higher but my ammeter smooths the value over time so a high peak of short duration will look like a smaller average value for longer.

But I am noticing is the compressor does not start immediately when the fridge is started. A few days ago I noticed it started after 7 minutes and I just thought that was standard. But recently it would not start for a good couple hours and then eventually started on its own. I think the fridge retries the compressor every 7 minutes or so.

So this looks like a problem where the compressor is either meeting too much resistance, or the inverter board supplying power is deficient.

This would explain the random long periods of warming in the fridge. This is probably when the compressor is not able to turn on again and misses a number of cycles, then eventually can start.

I think there is a component in the sealed refrigerant system that allows pressure to bleed back from the high side to the low side gradually making it easier for a compressor to start. Perhaps this component is plugged partially or fully. But regardless even if this is the issue it's not one that I can fix because if I cut into the sealed system I have no way of sealing it again.

Latest temperature charts below.

First 3 are freezer temp from last 24 hrs, the day before, then the last month.

Last 2 are from the fridge, last 24 hrs and the last week.

Any ideas before I have to trash this fridge and go pony up 2 grand on a new one?  By the way this fridge is at least 10 yrs old, maybe 15.

[BaconCentric]

Not that anybody cares since there have been no replies here since mid November when appl.tech.29501 kindly made a suggestion, but...

 

I think I may have solved it.

Bad inverter board.

Before replacing inverter board it would cool from 60 deg F for maybe 8 hrs down to -10, then the compressor would fail to start and it would warm up for maybe 6 hrs to 60 deg again, then the cycle more or less repeats +/- a couple hours (first pic).

Now, after replacing the inverter board, it cooled down and has been holding steady (except for the expected defrosting spikes) for a good 12 hrs (see 2nd picture).

I'll keep an eye on it for another day or two before declaring victory.

 

 

[General Appliance]

Thank you for your post, I'm working on the same fridge with a similar problem.