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MZD2766GEB Maytag Side by Side not Defrosting

whfh99

Premium Member
Joined
Oct 28, 2010
Messages
2
Location
New Hampshire
Model Number
MZD2766GEB
Brand
Maytag
Age
More than 10 years
I have a 17 year old Maytag side-by-side refrigerator that had been working with no issue for the nine years we have had it (came with the house) until a few weeks ago when the fridge side was no longer cold. I cleaned out the back of the fridge and blew out all the dust bunnies (it was overdue for sure) and also noticed the evaporator inside the freezer was all iced up. I let it thaw out natually, did a continuity test on the defrost heater and got 20 ohms. From reading online, I thought it may be the automatic defrost control unit so I replaced that with an aftermarket unit. Started the fridge back up and about 3 days later, the evaporator had iced up again. I thawed it out again, tested the defrost heater element again (same resistance values), left the cover off over the evaporator and started the fridge up again. The evapoator blower has been running what seems like non stop since I started it up (maybe because I didn't put the cover on it?) and I can see the evaporator frosting up again. There is no food in the either the fridge or freezer now and I've felt along the door seals and do not feel and cold air plus with no food, there has been little opening and closing reducing the risk of someone leaving the door open a little.

From what I researched, it seems like the issue is the defrost circuit is not working (I can see frost on the defrost heater element currently) and the issue is either the defrost heater and thermostat or the auto defrost control. I replaced the defrost control but maybe that part was bad or despite my resistance test on the heater element, maybe it is still faulty and I should replace it? Could there be something else at fault that I'm missing? I'd prefer to fix this fridge if I can. I realize it's no spring chicken but fixing it if i can would spare me going through the process of getting a new one.
 

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Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
2,340
Location
Canada
noticed the evaporator inside the freezer was all iced up.
Clear "ice" or white, snow-like "frost"? It is an important distinction whose causes can be very different.


the issue is either the defrost heater and thermostat or the auto defrost control.
When you tested the heater was the defrost thermostat in the circuit so it was tested at the same time?


left the cover off over the evaporator and started the fridge up again.
The refrigerator will not function properly that way. All covers need to be in place.


Poor air flow across the evaporator can also cause it to frost excessively. If all components of the defrost system check out, someone might need to look into the evaporator motor's operation... after being fully reassembled.

Dan O.
 

whfh99

Premium Member
Joined
Oct 28, 2010
Messages
2
Location
New Hampshire
Definately white, frost like. The defrost thermostat wasn't in the circuit as I tested continity between just the two wires that went to the heater element. I can certainly do a continuity test with the defrost thermostat wires. What would I look for there? I was wondering about the fridge working without the covers. I suspect with the covers removed, there was really no 'airflow' over the evaporator this last time however, all covers were installed prior and it frosted over. I would assume even with the covers off, the defrost circuit would still 'try' to function and I could see frost hanging from the defrost heater element so I don't think it's been coming on at all.
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
2,340
Location
Canada
I can certainly do a continuity test with the defrost thermostat wires. What would I look for there?
It should have continuity when cold (possibly around 15 deg. F or lower depending on the actual specs of the component involved) and should open the circuit when gets warm (40 deg. F or above ... depending on its specs).


LINK > Refrigerator Defrist System Components

I would assume even with the covers off, the defrost circuit would still 'try' to function
I don't know the criteria used on that model to initiate a defrost but it should go into defrost ... eventually.

Dan O.
 
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