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The model on the door does not list the last letter in the model number. When I do a search there are four variants of this model. I am not sure if it makes a different with the defrost cycle. I read several threads on here and have gathered a few things. One of these three things are not working Defrost Heater Defrost Thermostat Adaptive Defrost Control About a year ago or so, I had a technician fix it. He said that it was the Defrost Thermostat. He said that he would have to order the part becaus the thermostart and heater are one part. He suggested replacing the thermostart only with a standard part by cutting and splicing this thermostart with this part. I remember him saying that he had to silicone the part to keep water out. About a few months (plus or minus) or so later the problem reappeared. So rather than call him back I defrosted the coils myself and put it back together. I was thinking I will do this to save the stuff in the freezer and address it later. Well I didn't. I have defrosted a few times since then. I am at a point now where the freezer becomes frosted in a week's time or so. So, what I have should have done a year a go or so, I need to do now. I need to address it and fix it. I did notice one thing of interest. There was a weird sound, maybe a buzzing sound coming from the refrigerator. Sound carries but it sounds like it was coming from that top panel in the refrigerator where the controls are located. It wouldnt happen all the time and it was loud enough that you could hear it with the door closed. I have not heard it for some and wondering if a part burned out or fried. I thought it might have been the light bulb. I dont know. They are both working. Before I start troubleshooting. I was wondering if anyone has any thoughts or suggestions. I found this service manual on a post from Gene. The manual does not reference the MZD models on the front page. I want to confirm that this is the proper manual. You can find the complete troubleshooting instructions in the Service manual(page 2-15).
Here are the break down diagrams for the Maytag refrigerator Model MZD2766GES Thanks Bill
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Probably a bad adaptive defrost board behind the control panel AP4070403 since the defrost thermostat was replaced.
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Can someone explain this:
Checking the Adaptive Defrost
Control
1. Disconnect the unit from the power
source. (Does this mean disconnect power to refrigerator?)
2. Open the fresh food door and remove
any items on the top shelf.
3. Remove the light shield and the temperature
control housing (see steps 3
and 4 replacing the timer).
4. Connect the refrigerator to a wattmeter. (Connect it where?)
5. Make sure compressor is running (cold
control closed). (How does the compressor run if it does not have a power source?)
6. Using an insulated number 22 jumper
wire short between L1 and Test; this will
put the refrigerator into a defrost for
approximately 23 minutes.
7. The watt meter should read between
500 to 600 watts depending on the
model.
Note: If the temperature control is open
(unit not running and you jumper L1 and
Test) the unit will cycle through the test
mode in two seconds and there will be no
watt draw. (Is this how you determine the adaptive board is defective?)
I apologize. I am not grasping this.
Thanks
Bill
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If the defrost thermostat and defrost heater is ok, I assume by default a bad adaptive defrost, this has never failed me.
The modern 1/8 hp or less compressors draw about 1.4 amp, hardly 600 wats for a 115 volt line.
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Thanks.
I assume I turn the refrigerator to off to check the resistance on the heater/defrost thermostat?
Do I need to unplug the refrigerator from the wall as well?
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I dropped the panel and un plugged the adaptive defrost control board I followed these instructions and got 22 ohms Set the ohmmeter to R x 1K scale and
connect the probes to the No. 2 and
No. 3 terminals of the disconnect plug.
5. The meter should read between 20 to
40 ohms. The resistance is not critical.
If there is continuity between terminals
No. 2 and 3, the defrost heater is in operative
condition. If there are no resistance
readings (open circuit) the defrost
heater and thermostat must be checked
individually.
I believe they are the orange and white wires. I did notice that if I connect the yellow and white wires I get 32 ohms.
It seems that the heater element is operative and that I need a new control board based on this?
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I noticed that the replacement part has a white plastic enclosure.
The original part didnt appear to have this case and appears to be built differently?
I havent tried to install it. The screw holes and connector appear to be the same.
I figured I would ask before I tried to install it this evening.
I received my part very quickly and I am very pleased with the support that I have received on this forum. This is by far the best consumer experience.
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Your new adaptive defrost board has a cover to keep moisture away from the pc board, improved design, should last longer, recomend putting a 1000 joule surge protector on your outlet to prevent future problems.
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