Warm Kenmore Refrigerator not defrosting

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  #1  
Old 11-30-08, 11:42 PM
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Unhappy Warm Kenmore Refrigerator not defrosting

A week ago my bottom-freezer Kenmore (model number 596.75232402) was warm (58) in the refrigerator compartment but the freezer was okay. After reading other posts on this site, I emptied out the freezer, took off the back panel, and found a solid wall of frost/ice.

I emptied the fridge out, unplugged it, and thawed it out completely, and it started back up again with both compartments nice and cold. However, this week when I look in the freezer I can see that the frost is building up again, and I'd guess I have another couple of days before the fridge is warm again.

My question is, what steps do I follow to track down the faulty component? I (and my wife) would really appreciate your advice.

Note: this fridge has a digital panel to control the fridge and freezer. I found the electrical chart under the front grill, and it included the directions on how to enter service mode and manually force a defrost cycle. The forced defrost cycle did not melt any of the frost/ice on the coils, even after four hours.

Thanks!
 
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  #2  
Old 12-01-08, 07:35 AM
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It could be 3 problems:

1. Bad defrost thermostat, which clips onto the cooling coil in compartment you found wall of ice. These defrost stats are usually an approx. quarter dia. size object with 2 wires, and they have op ranges printed on them that may say something like 36-55, or something like that. In order to test for bad, the test must be done when cold/iced and you should read continuity across wires. If open, it is shot. You can also unclip, unjack wire connectors, insert in crushed ice, and test.

This was problem on MY last frozen coils call not long ago, and new one fixed her up.

2. Defrost timer clock is not running or somehow contacts inside are bad.

3. Bad heater/element. You can disconnect leads to them that are back by your frozen coils and ohm test between each end with power to fridge disconnected.

4. IF frozen ice only confined to bottom area of coils, you may have plugged defrost line that does not let the thawed water out of freezer pan under the coils.

Check that stat first and post back finding so we can further instruct if necessary.
 
  #3  
Old 12-02-08, 09:28 PM
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Thanks for the very clear response! I emptied out the freezer and took a look around. When I realized I wasn't sure what was what, I went to the RepairClinic.com site that I saw mentioned elsewhere and looked at the pictures; it really helped.

The thermostat read >10kohm (as high as my meter goes) with frosty ice on it, so that's probably it?

I disconnected the heater element and stuck the meter across it and measured 6 ohms. According to the component specifications that I found under the fridge, the "evaporator heater" (same thing?) is supposed to read 29 ohms, plus or minus 5%. Is this also a problem?

I don't think it's a clogged defrost line. When I defrosted the fridge last week, there was a nice little puddle under the fridge, despite the (mostly dry) towels I had inside the freezer.

I've also attached a picture, in case it helps.


So, what's my next move?
 
  #4  
Old 12-03-08, 08:55 AM
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You may have four things that could cause this problem. You have an ADT (defrost timer device), thermistor, defrost limit switch, and defrost heater. If you have a reading on the defrost heater, it should be good. The most common problem is the thermistor, followed by the defrost limit switch. I really can't see from all the frost, but I think the thermistor is that little white thing in the upper right hand side. The defrost limit switch is the one ecman51 talked about. It will have two leads connected to it, and is in series with the heater. The other thing would be the ADT electronic device that turns on the defrost circuit as it is needed, located in the refrigerator section somewhere.

H.
 
  #5  
Old 12-03-08, 04:01 PM
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Originally Posted by pratsa View Post
The thermostat read >10kohm (as high as my meter goes) with frosty ice on it, so that's probably it?

So, what's my next move?
If you quickly tested it before it warmed back up, I'd say you found your problem. Your photo looks just like mine when I had the open stat. As I mentioned, I double checked mine by packing ice around it in bottom of sink and still found it "open".
 
  #6  
Old 12-03-08, 04:54 PM
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One thing I didn't mention is that when I ran the forced defrost, I could hear the compressor shut off. So I take this to mean that the control board is okay.

It seems like the current possibilities are the thermistor, thermostat, or the timer. I'll have to figure out where the timer is, and how to test it. Can you help with that?
 
  #7  
Old 12-03-08, 07:47 PM
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Correction!!

The thermostat is CLOSED when the freezer is cold. I was looking at the meter the wrong way last night.

So, summary:
Thermostat is closed when cold - seems okay.
Heater elements read 29 ohm - seems okay.

So I'm left with the thermostat or the timer. The timer is not in the freezer, and there's no exposed wiring on the thermostat, so I guess I'll have to open up the back of the fridge? I've got no problems doing so, but I don't want to unless that's the next idea.

Thanks
 
  #8  
Old 12-03-08, 08:44 PM
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Do a check on google for adaptive defrost timers, you can find out how and why they work, and how to test them. That board should be in the top of the refrigerator section, probably under some plastic covers.

H.
 
  #9  
Old 12-04-08, 06:40 AM
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I think the timer location of the bottom freezer model I worked on was behind the front grill right side.
 
  #10  
Old 12-04-08, 10:33 AM
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Icman51 is right if it is the old type of defrost timer. I assumed it was of the newer type adt type, since the temp controls were digital.

H.
 
  #11  
Old 12-04-08, 09:46 PM
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The tech specs mention the compressor, thermistor, evaporator fan, thermostat, evaporator heater, etc. but they do not mention a timer. They do mention the control board, and refer me to the control board section.

When I ran through the service tests, everything seemed to pass. However, I don't think I understood how things work as well as I do now. I just ran the "defrost thermostat & defrost circuit test", and the heater element heated right up and started to melt the frost. Tomorrow after work I'll go through the other tests and see if I can eliminate everything other than the culprit.

If it has something to do with an adaptive defrost timer, does that mean I'll have to replace the whole control board?
 
  #12  
Old 12-05-08, 06:20 AM
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Originally Posted by pratsa View Post
When I ran through the service tests, everything seemed to pass.
This is something new to me. What does this consist of? Is info supplied with a user manual that tells you what to push on a digital display? Does the info consist of one of those pages that has arrows where you do as the arrow say, and you follow the yes and nos?
 
  #13  
Old 12-05-08, 08:13 AM
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It's pretty similar to that, except it's just very short descriptions on the tech sheet that was supplied under the fridge. I wish it was a nice, detailed troubleshooting flowchart, but I guess that's too much to ask for...

There are 8 tests, and the first one is the one I mentioned earlier for the heater/thermostat. Another one opens and closes the damper, and I remember hearing that one working. I'll go through the others tonight and see what I can notice.
 
  #14  
Old 12-05-08, 09:00 AM
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You do not have a defrost timer, just the adaptive defrost control. Your refrigerator was manufactured by GE. Go to Appliance repairs, Appliancehelp, Appliances, repairs to dryers washers dishwashers fridges repairs microwaves ge maytag kenmore frigidaire westinghouse inglis, appliance how to take apart information, purchasing an appliance help, model number help, click on repair help, go to refrigerator repair. There you will see a link to open on GE Artica and other electronic refrigerators by GE. This shows all the testing for this model.
 
  #15  
Old 12-06-08, 01:10 PM
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Thanks for the link, there's a lot of info there! Actually, that site says my fridge is made by Amana (model # 596), which might come in handy.

I ran through the service tests, and I'm not sure what the results mean, but I have a guess.

  • Test 1 energizes the defrost circuit, and it passes that test. I touch the heater coil with a ice cube and it hisses and sizzles.
  • Test 3 activates the "Evaporator/Freezer Fan". I can hear and feel it turn on.
  • Test 4 tests the fresh food thermistor, and displays either Pass/Open/Closed. It passed.
  • Test 5 tests the freezer thermistor, and that passed.
  • Test 6 opens and closes the damper. I could hear it moving, so that's fine.
  • 7 and 8 just adjust the levels of cooling for fresh food and freezer, so I left them alone.

So, you'll notice I didn't mention Test 2. That's because this is the test that was a little weird.
Just like test 3 activates the freezer fan, test 2 is supposed to "operate the Compressor/Condenser Fan circuit." When I activated the test, I heard a relay click on the controller board, and nothing else. The compressor and fan did not start to make a sound, nor did they stop making sounds. There's just a constant hum, no change except for the relay clicking.

So, here's my theory:
During defrost, the heater element is supposed to heat up those coils back there and melt all the frost. At the same time, the compressor is supposed to stop cooling the air.
If the compressor failed to stop, would that the enough to prevent the heater element from completely melting the frost? In other words, if the circuit that's supposed to turn the compressor off failed to work, could that be my problem?

Any other thoughts? Should I get a new controller board, or is there something else I should test first to make sure? A $100 controller board is cheaper than a new fridge, but it's a big chunk of our household budget.

Thanks for the great help so far!
 
  #16  
Old 12-06-08, 02:18 PM
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If you can, check the compressor to make sure it is working.
Grab a cup as this takes a few minutes to perform.
Use a multi-meter (Radio Shack about $20.00) remove all components on the compressor to reveal three pins in a triangle shape.
First test is to set meter to ohms (horseshoe) place one meter lead on a good ground, the other lead jump from one pin to the next. Any reading and compressor is grounded.
Second test, go between any two pins and record their reading. Means windings are good. No reading, windings open.
If okay, replace the board. Beer 4U2
 
  #17  
Old 12-07-08, 12:12 PM
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I'll do that, but I have a question:
Right now, the freezer is frozen and the fridge is at 34F, so I would assume that it's okay. If there was something wrong with the compressor, wouldn't my fridge be warm?
 
  #18  
Old 12-07-08, 12:35 PM
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I thought you heard the compressor relay just clicking. My mistake, it was on the control board you heard it.
Google fridge doctor, he gives a complete guide to troubleshooting ADC.
 
  #19  
Old 12-07-08, 07:36 PM
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Well, it looks like the fridge doctor says that if the heater element and thermostat are working, then the problem's with the ADC. He shows it as being its own circuit board, but since I don't see anything like that I assume they've started just adding it to the main control board, right?
repairclinic.com doesn't show any other circuit boards besides the main one.
 
  #20  
Old 12-08-08, 06:27 AM
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The "Main Control Board" has the ADC in it.
 
  #21  
Old 12-09-08, 07:34 AM
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All right, I've got a new control board on it's way. I was planning to defrost the freezer manually before installing the new board, but is there any advantage to just putting the new board in as is and letting it do it own defrosting?
 
  #22  
Old 12-09-08, 11:41 AM
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Originally Posted by pratsa View Post
All right, I've got a new control board on it's way. I was planning to defrost the freezer manually before installing the new board, but is there any advantage to just putting the new board in as is and letting it do it own defrosting?
Best to start clean. When you buy it new there is no frost, so let's start from scratch.
 
  #23  
Old 01-21-09, 08:58 AM
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I always hate it when these threads end without the final word, so here it is.

It worked.

The board took extra time to arrive due to the huge ice storm in New England, but I took advantage of the two day power outage to defrost the freezer. It's been about a month, and the freezer's in great shape. I was really excited a day or two after putting in the new control board when I heard a tiny hiss coming from the freezer. I realized that was the sound of frost being melted, dripping on the heater coil and evaporating!

Thank you all for your help!
 
  #24  
Old 07-26-09, 10:53 AM
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Similar problem

I am experiencing the same problem with my Amana (Sears) bottom freezer fridge. I have defrosted it several times. When I put it on forced defrost, the defrost element does not heat up. I tested resistance - 30 Ohms, but the voltage to the heater was only 30 volts, which means the heater could only put out about 30 watts. So, I assume the voltage should be 120 Volts. What could be the cause of the low voltage??

Thanks
 
  #25  
Old 07-26-09, 02:07 PM
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try bypassing the defrost limit thermostat and see if the voltage improves, if not trace back to the circuit board and check the output there.
 
  #26  
Old 07-26-09, 02:34 PM
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low voltage

Thanks.

I plan to defrost the freezer tomorrow and I will bypass the thermostat and check the voltage. I have not taken a look at the infamous control module yet.
 
  #27  
Old 07-27-09, 09:48 AM
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Unhappy Defrost problems

Well, I took everything apart today. Put the fridge in forced defrost mode. Disconnected the defrost heater and measured 120V! Measured the defrost heater at 33 Ohms. But when i put the connectors together, no heat. At this point the only thing that makes any sense to me is that the pins are not making contact within the connectors. So, I connected one side and measured 120V across the other side. When I reconnected the second side and opened up the first, I get 120 Volts. This does not make any sense to me at all. Anyone have any ideas? At this point, I am considering cutting out the connectors and soldering the wires together to see if that helps. I would appreciate any ideas.

Thanks.
 
  #28  
Old 07-27-09, 03:24 PM
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What do you read across the heater if it's connected to the terminals/ Readings from terminal to the cabinet tell you nothing. When you reconnected, was the defrost limit thermostat in the circuit or out? What happens if you make a test cord and apply 120 volts directly to the heater from an outlet?
 
  #29  
Old 08-10-09, 07:01 AM
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bad defrost cycle, same symptoms

I am now having this same problem with my kenmore which matches the picture in this thread. I have been able to do the forced defrost after finding the "hidden" instructions up behind the front grill. The unit passed all the service mode tests and the forced defrost was successfull with hot to touch defrost element and hissing. Even before i discovered the hidden instructions i was able to establish continuity of the heater element and also establish the continuity of the defrost termination thermostat cold and then after holding it in my hand for a few minutes it warmed up and went open circuit. I'm hoping that entering the forced defrost will magically reset the defrost cycle and restorew the unit to proper operation but if not then it seems the problem has to be in the jaxx pcb. any one have any ideas????
 
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