Let me know if you have questions after seeing this. I hope Samsung will leave this alone for a while! It takes time to reconstruct!
Unfortunately, the thread and the post were deleted.. So, I'll recreate the message here. My fix has been in use since 4/12/19 and so far no problems. Defrost cycles seem to have normal spacing and duration and there have been no error codes. I think the original problem showed up because of a manufacturing process control failure (bad wire position crushing gasket) and Samsung should accept responsibility.
PLEASE LIKE THIS POST OR COMMENT ON IT IF YOU FIND IT USEFUL, AGREE or DISAGREE!
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ORIGINAL POST
Model RF26J7500SR/AA Evaporator Cover Seal Is Critical to prevent freeze-up
Various models may have different, even multiple causes and different solutions to deal with evaporator freeze-up and fan noise.
Here's my information and experience
Model #RF26J7500SR/AA
S/N: 0AF84BBG600383L (Parts supplier says this is the 4threvision of the model)
Purchase 3/30/16
Problems began 9/29/17 (loud fan noise, back of fridge compartment)
Problem solved 4/12/19 (Replaced crushed gasket section, right side of evaporator cover near the defrost sensor location.)
There are some good videos that show you how to open up the evaporator compartment in the back of the main fridge section. I have done this several times while trying various recommended solutions that didn't work.
For now, I'll get directly to the point. A week ago, I had removed the evaporator cover again. I noticed a problem on the back of the evaporator cover near the defrost sensor location. The gasket on the evaporator cover had been crushed.
I found some .05 mm thick foam sheet in my packing supplies. I rolled the sheet material into a compact sausage to match the dimensions of the remaining intact gasket. I loosely taped the rolled foam to the evaporator cover in the gap and reinstalled the cover. The fix was a success. I may not know for months if it’s a good long term fix. But in the short term, it's a resounding success.
How do I know it was a success without the use of extra test equipment? There's a control panel pad push sequence that can reveal any error codes. Here's how to do it:
- Briefly press Fridge. That lights up the display
- Press and hold simultaneously Freezer and Fridgefor 9 seconds
While you are holding, the entire display will flash all elements a couple times, then go dark.
If everything is okay, you'll hear two tones descending.
If all is NOT okay, you'll see one or more error codes.
If you see -25E, then you have a defrost problem.
This is a really BIG problem! Once there has been a -25E code, the refrigerator section defrost WILL NOT RUN AGAIN until you unplug the power and plug it back in again! The freezer defrost will continue to work. Ultimately, with no defrost happening in the fridge section, ice builds up in the evaporator area and the dreaded fan buzz starts up.
Anyway, after fixing the gasket, the -25E error code has not returned.
Below are photos of what I found and what I did. After the photos are my thoughts about what went wrong and how the problems started.
PHOTOS
What went wrong?
The first photo shows what I found the first time I opened the evaporator compartment on 9/29/16. What drew my attention at the time was the hard ice buildup even after I had turned off the fridge for several hours. I missed an important detail at the time. The defrost sensor and heater wires had been positioned in the path of the gasket sealing an air distribution channel. This gasket is supposed to keep air from leaking to and from the inner part of the evaporator compartment.
The foam seal was designed to mate with a flat surface, not conform to an uneven surface such as wires running under it and even crossing it. You can see from the photo of the gasket that it did not recover from getting crushed.
Crushed gasket due to bad cable lead
The seal must have worked somewhat because the refrigerator took 18 months to fail. Unfortunately, I did not know how to read error codes before the evaporator cover came off the first time and changes were made. Over many months, perhaps the defroster wasn't running long enough and ice built up gradually. Perhaps moist air was leaking into the evaporator compartment depositing more frost and increasing the defroster load beyond what it was capable of managing.
Patched gasket shown above
Failure that started with a leaking seal
My theory is that with warming and cooling cycles, expansion and contraction, the seal got worse over time to the point that the defroster had to run until it timed out, and registered a -25E error. That would shut off the defroster entirely, so it was only a matter of time that frost built up on the evaporator and interfered with the fan.
What determines the length of a defrost session?
The defrost sensor is a thermistor. Resistance increases as the thermistor gets colder, and resistance decreases as it gets warmer. The refrigerator control circuits monitor the thermistor while a defrost cycle is running and when the temperature is "warm enough", it recognizes success and turns off the defrost heater. In some units, that cutoff temperature is 63ºF. If the heater circuit is bad, the thermistor is bad, or control circuits or wiring are bad, then the defroster doesn't work normally.
Look at the photos. The defrost sensor is close to the problem sealing gasket. The sensor was designed to measure the temperature with the fan off, the heating coil on, and the chamber sealed from drafts. If the seal was bad, that could lead to so much ice build up that the defroster couldn't handle it. Or, air moving from outside the chamber might prevent the air near the sensor from warming up adequately to reach the defrost shutoff temperature.
What triggers the -25E defrost error?
It is simple. If the evaporator chamber doesn't warm up to 63º F within 90 minutes, the defrost system times out. How do I know that timeout occurs at 90 minutes? Advanced test equipment!
Power use graph shows dramatic change after gasket was repaired
I have the ability to monitor refrigerator power use moment-by-moment and see a graph of the results over time via a web-based interface. That made it very easy to show the before-and-after when I made changes. As soon as I realized that the crushed gasket and the position of wiring had caused the damage, I rerouted the wires away from the gasket and improvised a gasket repair. The graphs mostly speak for themselves. The refrigerator compartment defrost wire uses a steady 108± watts. The freezer defrost often starts a cycle, showing a spike to about 480 watts (108 watts of that for fridge). I think the refrigerator defrost starts at the same time as the freezer. Sometimes the refrigerator has its own defrost cycle without another freezer cycle. The flat profile at 108 watts is easily recognized as is the long plateau if the defroster times out.
Repair Background
In early January, a well-respected independent appliance repair person made several adjustments to the fridge for me. I had previously adjusted it to lift the front wheels off the floor. The tech checked the drain tubes and added a probe carrying heat to the drain opening under the evaporator assuring it wouldn't freeze. The defrost sensor was moved to the refrigerant outlet tube, a standard recommendation. By late March, the fan noise returned.
New Defrost Sensor and first graph
In early April 2019, I installed a new defrost sensor in the preferred location on the refrigerant outlet tube. At that time I set up the power use monitoring. As shown in the first graph below, the defrost ran for 90 minutes and timed out. Clearly the defrost circuit was working because it was drawing the expected amount of power.
GRAPH AFTER NEW SENSOR
After this failure, I wondered if the sensor needed to be closer to the defrost heat source and back to the factory location. Then I noticed the crushed gasket on the evaporator cover panel. I repositioned the defrost sensor wire and the defrost coil away from the path of the gasket and improvised the gasket repair. Below is the graphed result showing no more defroster timeouts. After 9 hours to cool the fridge to a steady state, there was one long 56 minute defrost cycle. Ever since then, defrosts have ranged 30-45 minutes a few times a day. See below the graph for more discussion.
Graph after gasket repair shown above
After this failure, I wondered if the sensor needed to be closer to the defrost heat source and back to the factory location. Then I noticed the crushed gasket on the evaporator cover panel. I repositioned the defrost sensor wire and the defrost coil away from the path of the gasket and improvised the gasket repair. Below is the graphed result showing no more defroster timeouts. After 9 hours to cool the fridge to a steady state, there was one long 56 minute defrost cycle. Ever since then, defrosts have ranged 30-45 minutes a few times a day. See below the graph for more discussion.
Epilogue 5/31/19
The gasket problem seems like the critical one for my fridge. Condensate (water) draining could be the most important for some fridges. I suspect that moving the defrost sensor may help some people, but I'm guessing that strategy is really just compensating for another problem like a bad evaporator cover seal. Whatever works…. WORKS!
Epilogue 7/1/21 The repair continues to work fine!
