Samsung Fridge RF18HFENBSRAA Display temp not matching actual

[MarkR]

HI All,

I did lots of searches here and everywhere over the last few months.  while they provided me some paths of action, my problem still exists.

I've become a DYI expert on this fridge, really learned a lot. I'm an experienced Tech of 28 yrs and know my way around components, diagrams, low and hi power. Hate to say I used to carry an oscilloscope! I'm pretty technically versed, albeit not specifically on appliances.

Fridge is a like-new 2017 I got from a friend dirt cheap as he couldn't figure out his Frosting coil problem. I did by installing the "Fix Kit" by Samsung which was a heater probe, seals and I also placed addt'l copper coils in the drain tray. The "duck-Bill" drain tubes were also updated. No wires are compressing the foam seals etc. All checked and verified.

Now I've been running the fridge since this spring, and its generally doing ok now. But I discovered by putting thermostats in the fridge, that it runs warmer than what the digital display says. The display is supposed to show actual temperature, while pushing the button you can change the set-point. I have it at 34. When I power it up, it does indeed read room temp, then the display goes slowly down to 34 as it cools, normally.  34 in the display. About "40" in the box on multiple thermostats. And you can sometimes tell items are not really cold. If the house is warmer, it may be a tick above 40.

I've Verified or replaced the following: 

• No error codes displayed in Diags Mode
• compressor area is super clean with original backplate etc.
• No freezing up on the condenser coil
• Heater energizes on Forced Defrost mode
• compressor comes on in Forced Mode
• Fan is working ok, verified by pypassing door switch and have good air flow
• Measured ( and also replaced) the Thermistor Sensors at various temps that match the Mfg impedance charts..Both Defrost sensor, Compartment sensor(but replaced both)
• Verified the Heater Bi metal thermal fuse opens and closes at cold & hot-Good.
• New complete Condensor back-panel. (Didnt like the conditon of the foam from prior owner/service work), which had the new fan, and box Temp sensor.

This week, I found the Temp OFFSET Calibration information. I was able to get into the correct Fridge "1" mode and I tried some offsets. First 6 (for a -6 offset) for a couple days. Then 15 for a +8 Temp Offset.

Interestingly, neither end of the offset scale had much, if any, impact. I was surprised- I thought this would do the trick. Temps continue to hover around 40 on thermostats in compartment, while the display reads 34, and is set to 34. 

The Fridge IS ABSOLUTELY CAPABLE of going lower! When I hit Power Cool, after awhile, I can get the display to read 25, while the thermostats also read 25( or closely matching what the display is showing).

I was thinking I would just live with this for now, But I'm tenacious.  Am I getting close to replacing the Main board? Cant fathom why the display always will settle at reading 34, while the box is always 6-7 degrees higher.

 

Appreciate any input from experience

 

Thanks

 

 

 

[MarkR]

Oh, by the way that model is a french door style, lower freezer unit. "Dual Cooling". No issues with Freezer or Ice. Just the above described symptom with Fridge.

[EthanRanft]

I’ve had one experience with something similar. But unfortunately I never found a solution. The issue was only really in the freezer though, fridge seemed fine. So freezer display would read 0 while the actual temp would be 20-25. Thermistors all tested good with both voltage and resistance checks, and after unplugging the refrigerator and then plugging back in, it would correct temps for awhile but then gradually go back to 0 with no change in temp. Sad to say, I replaced the control board and thermistor for good measure, with no effect. After looking at the evaporator, I decided it must’ve been a sealed system problem. But because of the situation, I couldn’t verify further.

My guess is that some Samsung’s are programmed to be very forgiving when it comes to reporting temps, so as not to alarm customers for “minor” temperature fluctuations.

My only suggestion is save replacing the main control as a last resort. There may be other issues at play that have nothing to do with the reported temps on the display

[MarkR]

Thanks Ethan, 

 

Seems to be a good one. I could digest fluctuations as it it did slight normal detected warming, with compressor kicking in, and seeing temps drop. I'm fairly sure it hold steady at 40, while set at 34 and displaying 34, without much fluctuation.

Got me baffled good. I'm willing to accept it and just live with it for now. I have a feeling next spring/summer when the house is warmer-it may not recover and hold at 40 after the door is opened a few times.