Fridge WRS321SDHZ08 "Adaptive Defrost Controller" function not working, anyone understands its inner workings?

[Rame]

How do I force the defrost mode? 

[GEDavis2]

Where is the thermistor mounted? I am sure its obvious but I can't seem to locate it.

Thanks!

[benstickell]

Can you provide the schematic please?

 

[Nathaniel Peterson]

2 hours ago, benstickell said:

Can you provide the schematic please?

 

It's on site

[Budget Appliance Repair]

14 hours ago, Nathaniel Peterson said:

It's on site

Not for a person with "Grasshoppah" status - The forum topic for schematics and tech sheets is only for paying members or MST students.

[isaacjc]

Does anyone know the fix for this? The same thing is happening with mine, I know absolutely nothing about fridge repair, but wanted to try and fix ours (which was also manufactured in 2022), was hoping it was just the evap fan motor (it wasn't) I was going to test the connector for the defrost heater for continuity but my cheap harbor freight multimeter had a broken negative probe. Guess that will have to wait until tomorrow. 

It's still covered under the limited warranty but that only covers the compressor so i'm sol there. Any info would be awesome!

[isaacjc]

Going to add a few things from my above post since I've been working on mine.

I found this site that has some exploded diagram views with part numbers, I did not use them to purchase any parts but it did help to identify part numbers
Whirlpool WRS321SDHZ08 Parts List | Coast Appliance Parts

I found this video that shows you how to get into diagnostic mode

And I was able to test the defrost mode, like others here it did work during diagnostics. I am going to replace the thermistor (the one near the evap coil, assuming can find it) today when the part comes in 
here is the 8 dollar thermistor I got:
Amazon.com: WPW10384183 W10384183 Refrigerator Thermistor - Replacement Parts Compatible with Whirlpool Kenmore, 2118228 Freezer Inside Parts Temperature Sensor : Appliances
 

someone asked about the thermistor location, this might help it's part 12, not sure if thats where it is in relatin or not but it kind of seems like everything lines up

 

i'll update this post if I get things going again, I was hoping to avoid buying a new fridge, and it seems numerous others are having issues with this year/model. 

Does anyone have a full list of the diagnostic mode tests? the video description has a dead link, and im not able to find a good set of diagnostic test/instructions anywhere. 
 

[Nathaniel Peterson]

4 hours ago, isaacjc said:

Going to add a few things from my above post since I've been working on mine.

I found this site that has some exploded diagram views with part numbers, I did not use them to purchase any parts but it did help to identify part numbers
Whirlpool WRS321SDHZ08 Parts List | Coast Appliance Parts

I found this video that shows you how to get into diagnostic mode

And I was able to test the defrost mode, like others here it did work during diagnostics. I am going to replace the thermistor (the one near the evap coil, assuming can find it) today when the part comes in 
here is the 8 dollar thermistor I got:
Amazon.com: WPW10384183 W10384183 Refrigerator Thermistor - Replacement Parts Compatible with Whirlpool Kenmore, 2118228 Freezer Inside Parts Temperature Sensor : Appliances
 

someone asked about the thermistor location, this might help it's part 12, not sure if thats where it is in relatin or not but it kind of seems like everything lines up

 

i'll update this post if I get things going again, I was hoping to avoid buying a new fridge, and it seems numerous others are having issues with this year/model. 

Does anyone have a full list of the diagnostic mode tests? the video description has a dead link, and im not able to find a good set of diagnostic test/instructions anywhere. 
 

That's the correct part number. Just an FYI some of these Whirlpool sxs's have a thermistor in the freezer air tower at the upper right hand corner of the freezer. Doubt it on this one or you would've seen it on the parts diagram.Make sure you use a zip tie and put the thermistor in the exact location or you'll have temperature issues in the freezer section.

[isaacjc]

On 10/21/2024 at 7:56 AM, GEDavis2 said:

Where is the thermistor mounted? I am sure its obvious but I can't seem to locate it.

Thanks!

top right corner, I just replaced mine today, not sure if anyone will ever come back to this or some other poor sucker has the same fridge and will run into the same thing so i'm just going to keep updating this thread until I give up or fix it. New thermistor is in place and im hoping for the best. I left the back off so I could monitor the ice buildup we'll see what happens. I did not remove the clip/ziptie it down to the coil, if it freezes up again, i'll try that next.
 

[isaacjc]

4 hours ago, Nathaniel Peterson said:

That's the correct part number. Just an FYI some of these Whirlpool sxs's have a thermistor in the freezer air tower at the upper right hand corner of the freezer. Doubt it on this one or you would've seen it on the parts diagram.Make sure you use a zip tie and put the thermistor in the exact location or you'll have temperature issues in the freezer section.

Thank you! i'm going to double check the location now, I didnt zip tie it, maybe I should just do it while the backing is off but the clip felt solid.

Also the old thermistor was getting like 1.3 ohm, new one was getting over 2, both were room temp when checked, so maybe (hopefully) that'll get me going again.

 

[Budget Appliance Repair]

@isaacjc You need to replace the freezer evaporator cover to reliably test that you have fixed your problem.

If you don't the airflow over the evaporator is not flowing correctly.

[isaacjc]

3 hours ago, Budget Appliance Repair said:

@isaacjc You need to replace the freezer evaporator cover to reliably test that you have fixed your problem.

If you don't the airflow over the evaporator is not flowing correctly.

Will do. it was frosted up this morning so I wasn't having high hopes. Im sure i'll have to manually defrost it now, make sure its' clear (maybe ziptie the thermistor on this time?) and then close it up. Was hoping leaving it open would at least allow me to keep an eye on it.

[Econo Appliance]

I'm working on one of these right now.    Long story short,   heater ohms out OK but doesnt get voltage from board during forced defrost.     Defrost thermistor failed OBD test 1st try but oddly passes 2nd, 3rd 4th try.  Passes bench test but I dont trust bench test.    Replaced thermistor as hail mary but same symptoms 1 week later.   No defrost voltage from ACU board on demand.   Board on order.

Edited April 12 by Econo Appliance

[isaacjc]

On 4/11/2025 at 8:37 PM, Econo Appliance said:

I'm working on one of these right now.    Long story short,   heater ohms out OK but doesnt get voltage from board during forced defrost.     Defrost thermistor failed OBD test 1st try but oddly passes 2nd, 3rd 4th try.  Passes bench test but I dont trust bench test.    Replaced thermistor as hail mary but same symptoms 1 week later.   No defrost voltage from ACU board on demand.   Board on order.

What part number did you order? 
I'm about ready to just toss the thing out the door and buy a new one. I put the back on mine and hoping for the best but i'm not expecting much.

[Econo Appliance]

45 minutes ago, isaacjc said:

What part number did you order? 
I'm about ready to just toss the thing out the door and buy a new one. I put the back on mine and hoping for the best but i'm not expecting much.

The model number I'm working on has one digit different than the model in the title, so I don't want to give out wrong part #s. If you order any parts you want to order it for your exact model.    

Also for a control board, you don't want to buy it as a hail mary. You want to do enough Diagnostics to where youre confident the board is at fault.

[66fomocoman]

Anyone come up with a solution for this we have one acting exactly as described. It will work for a month or so and then freezes over because it doesn't defrost. we have replaced the board twice for not providing power in forced defrost. The defrost thermistor tests good when checked. I'm thinking we are going to try replacing the thermistor as a HAIL MARY!!! Anyone been successful with another direction?

[66fomocoman]

Anyone come up with a solution for this we have one acting exactly as described. It will work for a month or so and then freezes over because it doesn't defrost. we have replaced the board twice for not providing power in forced defrost. The defrost thermistor tests good when checked. I'm thinking we are going to try replacing the thermistor as a HAIL MARY!!! Anyone been successful with another direction?

[isaacjc]

On 5/2/2025 at 2:29 PM, 66fomocoman said:

Anyone come up with a solution for this we have one acting exactly as described. It will work for a month or so and then freezes over because it doesn't defrost. we have replaced the board twice for not providing power in forced defrost. The defrost thermistor tests good when checked. I'm thinking we are going to try replacing the thermistor as a HAIL MARY!!! Anyone been successful with another direction?

Sorry for the late response here, hope you see this. I replaced my thermistor (the one near the evap fan motor on April 10th, so far, so good. I did not zip-tie the thermistor directly to the coil like others have suggested. I STILL haven't put all the shelves back yet because they were a pita to remove, but so far so good and no ice buildup. Here is a link to the part I purchased:

https://a.co/d/aUt1Elq
 

oh one more thing to note! I actually moved the thermistor over a tad from where it was, it was closer to the rounded turn of the coil, I moved it so it was more on the straight part of the coil, I was hoping it just wasn't making a good connection in addition to being bad. Anyway, I apparently don't have a picture of the new one on in the new spot, but I tried to highlight it in a box there for you. 

 

Hope it helps!

[Econo Appliance]

Thank you for updating, the more information the better!

I have repaired two of this model now, both were not defrosting.  One was electronic board, the other was a loose wire in the harness just above the evaporator.  Give all the plugs and connectors a gentle tug.

I have a feeling we will start to see many more of these.

Edited May 26 by Econo Appliance

[MrApplianceMatt]

5 hours ago, Econo Appliance said:

Thank you for updating, the more information the better!

I have repaired two of this model now, both were not defrosting.  One was electronic board, the other was a loose wire in the harness just above the evaporator.  Give all the plugs and connectors a gentle tug.

I have a feeling we will start to see many more of these.

These harnesses go bad too. The thermal fuse cuts out. I have also seen a few with evap thermistors showing 50 degrees while buried in ice. I have found in these SxS units that they will sometimes seem to default to timed defrost if the thermistor is unplugged. I have also seen the backed out connector on these and given my experience with them I typically quote the harness and the thermistor regardless of which of those 3 failures occurred because the harness and the thermistor have updated part numbers.