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lucyluc67

how to install my new adaptive defrost control board

98 posts in this topic

I too have the defrost failure on my 2001 Maytag MSD2756GEW, the way I do to manually defrost is to make an AC connector across the Heater Element and apply 120V AC to it, you don't have to remove any content from the fridge. I do this once every 6 to 10 days for about 30 minutes while researching and waiting on Maytag's answer. (Got their answer back, refuse to assist since my warranty expired! I paid $1,700 in 2001 for Maytag name, this will be my last Maytag I assure you)

When short out TST and L1, did not hear click. Replaced the relay, and micro controller, still don't hear the click, will look into the relay driver circuitry and post back my findings.

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[user=2851]jackpai[/user] wrote:

I too have the defrost failure on my 2001 Maytag MSD2756GEW, the way I do to manually defrost is to make an AC connector across the Heater Element and apply 120V AC to it, you don't have to remove any content from the fridge. I do this once every 6 to 10 days for about 30 minutes while researching and waiting on Maytag's answer. (Got their answer back, refuse to assist since my warranty expired! I paid $1,700 in 2001 for Maytag name, this will be my last Maytag I assure you)

When short out TST and L1, did not hear click. Replaced the relay, and micro controller, still don't hear the click, will look into the relay driver circuitry and post back my findings.

Make sure you have made metal to metal contact when shorting out the test & L1 pins since there is a coating on the circuit board and pins to prevent moisture from causing havoc on the circuit board. You can check this with an ohmmeter.

You should also check that both your fans are running (evaporator & condensor) when the fridge is running.

I found the problem with my Jenn-air to be an intermittent termisitor and a condensor fan motor which sometimes worked and sometimes didn't work. After replaced both I have a working fridge again.

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Finally it's fixed, the ADC board clicks when shorting L1 and Test, 23 minute is the cycle of forced defrosting. Check AC across the heat element and across the whole heat assembly you will know if the termister is faulty. The culprit was the relay. Notice I replaced it along with the micro controller all together, which is a bad thing to do and I had a such bad luck, the new replacement controller was defective! After checking all parts on the board I decided to replace again the micro controller, bingo!

I used a higher rating relay, about twice as high as the original one with same footprint, it fits well.

Thanks for all the help from you folks, couldn't have done it without you guys.

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I have the same problem with the defrost cycle and need help diagnosing if it is the control board or the thermostat/element.

Here are the facts:

1)The first time I jumpted L1 and test the defrost cycle went on for about 20 minutes(removed back wall to confirm this).

2)Subsequent tries (while frozen over) stopped the motor but did not turn on the element).

3)There are no burn marks on the board to indicate a burnout.

4)The resistance on the thermostat measured 240k ohms with slight fluctuation +- 20k between hot (room temp.) and cold (15 degrees).

5)The 2 year full waranty just expired (my luck).

Can you tell me definitively samurai if the board or the thermostat is the culprit, or, do you have any further diagnostics to confirm which component is at fault?

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Shogun, do we know what brand your box is and the model number??

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Sorry how stupid of me. Forgive me. Maytag Side by Side MSD2458GEW.

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Best way is to check the defrost heater and the defrost termination thermostat with your ohm meter with the box un-plugged.  If they test good then you have the ADC left as the problem.

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If the defrost thermostat measured 240K then it is open. Maytag uses a thermostat with a 240K ohm resistor in parallel to the contacts. This is used to simply diagnosis. Without having to expose the evaporator take an ohms reading between blue on the cold control (power off ) and the yellow wire on the adaptive defrost control (remove the connector plug - isolate) if you get 240k ohms plus the value of the heater (approx 20 ohms if O.K.) this indicates the defrost thermostat is open. If you get just the value of the heater this indicates the defrost thermostat is closed. Of course if your ohms reading shows infinity (no continuity) the heater is open. This can all be done by dropping the control panel of either the top mount or SxSides and accessing the cold control and ADC. Take a look at the schematic - simple - eh? For a partial schematic go to: http://www.kwantlentrades.com/appliancerepair/technology.htm  and scroll down to the diagram. Hope this helps

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[user=3111]shogun[/user] wrote:

I have the same problem with the defrost cycle and need help diagnosing if it is the control board or the thermostat/element.

Here are the facts:

1)The first time I jumpted L1 and test the defrost cycle went on for about 20 minutes(removed back wall to confirm this).

2)Subsequent tries (while frozen over) stopped the motor but did not turn on the element).

3)There are no burn marks on the board to indicate a burnout.

4)The resistance on the thermostat measured 240k ohms with slight fluctuation +- 20k between hot (room temp.) and cold (15 degrees).

5)The 2 year full waranty just expired (my luck).

Can you tell me definitively samurai if the board or the thermostat is the culprit, or, do you have any further diagnostics to confirm which component is at fault?

To confirm your facts, you did see the heater glowing when you forced the 20-minute defrost cycle and the evaporator was frozen at the time of testing.  Then subsequent tries failed to trun on heater when evaporator was iced over.  Am I correct in interpretating your facts?

The thermostat will close when it's iced over, the heat element will be energized when defrost cycle active.  When ice started melting to a certain point, the thermostat will open to prevent further defrosting regardless the cycle is active or not.

The best way to find out exactly what's wrong is to measure the voltatge between L1 and the DEF HTR when plugged in and in defrost cycle, make sure there's 120V AC.  Be very careful to do this due to risk associated, depends on your electrical skills.   Or you can remove the board, and apply 24V DC (12V should be able to do it too) to the relay coil and measure the continuity between the SPDT's pole and Def Heat (3 leads, one pole, one NC to compressor and one NO to heater).  The relay could click but not make good contacts everytime to energize the heat assembly.

From what you observed, you may have a bad relay or an intermittant teministor.  If you can measure 120V AC or good continuity on relay everytime it clicks, then you have a bad terministor. 

 

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Yes your interpretation is exactly right.

It will take me some time to digest and follow your instructions since my knowledge of electronics is fairly basic, but you have given me a good start and I should be able to handle it.

If the culprit is a bad relay or terministor, is the solution to replace the whole board, or just the defective link in the chain?

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To Jakpai, kwantlenappliance, and Pegi here is the end of the story. The defrost thermostat was indeed the culprit not the control board.

I devised my own test. I removed the defrost assembly and placed the thermostat in a cup of water in a different freezer. When it was frozen solid I tested for resistance. There was no change in the reading and if that wasn't cold enough then I don't know what is.

Just to be sure, I ordered a control board at the same time which I have since returned.

And they lived happily ever after.

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my coils are filled with "snow"

OK, after reading these messages, it seems my ADC is bad.

(my bad, I once or twice tried using a 2000 W power inverter to power the fridge in case of power outage) must have fused the "run" contacts.

My question is how do I get to the ADC?

The big plastic cover over the main temp control won't seem to come off.

I see the tabs holding it, but can't fiqure out which way / what to do.

I tried sliding it forward while pulling down, ect.

MSD2756AEW

thanks

 

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Remove the top shelf inside the beer compartment so you can stick your head inside and turn it to the sky.  The ADC control is in the that top-most control compartment, right hand side.  Start by unplugging the refrigerator

There are two sets of screws,a Phillips pair, and another 1/4" pair, toward the front that need to be removed.  There's also a pair of 1/4" screws on the back way that need to come out.  This diagram might illustrate it better. 

Now, here's the tricky part.  To pull the control plate tray out, you need to pull the tray down and toward you at the same time.  It's tricky until you get the hang of it.  Remember: finesse, not force.  You're dealing with cheap plastic-- if you force it too much, it'll break. 

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"Remove the top shelf inside the beer compartment..."

 

what to do with all this beer, what to do.....

thanks, got it, but no screws on this model, not much finesse either.

The trick was to "bow" the plate while pulling down and forward on both sides at once.

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Good job, I knowed you could do it! :cheers:

BTW, running your fridge on an inverter would NOT cause the ADC board to fry; it fried because it's one of the Achilles Heels on this machine. Common fail item. You are one of millions.

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I read with great interest all the replies and have some questions of my own.

What does it mean if the reading between L1 and Def Htr reads 0 (not 120V AC)?

I tested for the resistance after running the fridge for 24 h since I thawed the whole thing, and got +/- 240K ohms, meaning that the thermostat is open.

I replace the relay on the ADC and tried to trigger the defrost cycle by jumping L1 and Test. The relay does a buzzing sound, almost like a timer, but the defrost element does not get hot.

Could you help?

BTW what is a terministor?

Thanks

 

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[user=0]Dlecocq[/user] wrote:

What does it mean if the reading between L1 and Def Htr reads 0 (not 120V AC)?

Assuming your meter is set to read AC voltage, it means that there is the same electrical potential at L1 and Def Htr == usually means the board is in defrost mode, trying to energize the heating elements.

I replace the relay on the ADC and tried to trigger the defrost cycle by jumping L1 and Test. The relay does a buzzing sound, almost like a timer, but the defrost element does not get hot.

Not sure about that buzzing bidness-- got too much o' that going on my head! Speculation: it's the wrong relay for the application. Sounds like a well-known phenomenon called "relay bounce" where the improperly energized coil in the relay causes the relay arm to bounce on the contact, rather than stay put, resulting in a poor connection.

BTW what is a terministor?

A solid state device commonly used to measure temperature i refrigerators, ovens, dryers, and dishwashers. And extended application is to make a solid state start relay in compressors.

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Hi

Thank you for your quick reply. My fridge is a Jennair, side x side, JCD2289ATW and is building frost over time. Following the provided instructions, I did the tests.

When thawed, the resistance was 20 ohms (I assumed the thermostat is closed as explained); when frozen the resistance was 240k ohms with variations as I recall it (meaning open). I did additional tests on this resistance thing as follows:

Test 1A

Fridge compartment, fridge plugged in the electrical outlet, freezer control to off position but with lots of frost on the coil.

Meter on 2000 k ohm,

Common (black) on blue wire (at the connector level) and red on yellow terminal of ADC

I read Minus 240k ohm with variations

Test 1B

Common (black) on yellow terminal of ADC and red on blue wire (at the connector)

I read 550 or so.

Test 1C

Common (black) on yellow wire and red on blue wire near the Coil in the freezer

Common (black) on blue wire and red on yellow wire near the Coil in the freezer

Same results as Test 1A/1B

Test 1D

Unplugged the defrost assembly and tested the assembly only

I read 243k ohm.

 

The reading I did between L1 and Def Htr was on the AC scale of the meter set at 750V. I tested again, as follows.

Test 2A

Fridge plugged in the electrical outlet, freezer control to off position.

I read 120v.

Test 2B

Freezer control and refrigerator control to mid position.

L1 and test briefly jumped to trigger defrost (as in Jackpai’s explanation)

I read 0v.

Test 2C

Freezer control and refrigerator control to mid position.

Not in defrost cycle.

I read 0v.

Your explanation seems to apply to my tests but I’m puzzled by Jackpai’s explanation because different results are obtained. Being a novice at electronics, I may not have completely understood Jackpai’s test!

Can the fridge be plugged-in, in defrost cycle and have the freezer control in the off position, all at the same time and read 120v?

 

I checked the new relay and found out it is the twin brother of the original (JW1FSN-DC24V).

I’m at a loss here! Do you have more tests to recommend? What do you think is the culprit? Is it the terministor? And where is this thing located?

Is the evaporator fan always on?

Many thanks in advance!:huh:

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I have a Maytag MSD2756AEW and had the same defrost problem.

I drew a schematic of the ADC and found the cause and fix for the "buzzing relay"

It's a bad electrolytic capacitor, C2,  22uF @50v

Try jumpering in a good one across it. (there is a protective coating over the entire board)

Watch the polarity and also be careful, the minus (-) side of the cap is connected to L1 120v HOT side of the power line.

I drew the schematic with MS Paint, and will soon draw it  with a schematic program and upload it here.  (a few messages below)

 

also, neither the compressor nor the defrost heater will work when the temp control is turned down (but the relay will still energize)  try it at max cooling setting.

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Way to go, Reg! Excellent information-- that earned you a promotion. :cheers:

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I have a freezer coil that was completely plugged with frost.  I bought a new defrost coil, same problem 7 days later.

It is a Maytag MSD2756AEW sxs, 4 years old.

I have a voltmeter, but not sure which contacts to use to test for the resistence.  I will take a closer look, there mat be only 2 wires.  I have the Frig section top plate off, that was a pain to remove, one of the sides seemed glued together.

You guys are motivating me to fix it myself, thanks.  Any tips would be great!

Doug

 

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Maytag, probably a bad ADC, these have known problems, located up in the food section in the housing your controls are located...

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Ref. # 13 in this breakdown, part number will be 61005988.

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I shorted L1 and test and got nothing, no pop (no snap, crackle or pop).

Doug

 

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Click here to order this part......

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