FIXED MBB2256GES Bottom Freezer Not Defrosting

solarsurf

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Oct 17, 2009
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Location
New Jersey
Model Number
MBB2256GES
Brand
Maytag
Age
6-10 years
My Maytag MBB2256GES bottom freezer is not defrosting. How can I determine if the problem is a bad defrost timer or bad heater? Also, where are these parts located?
 

Jake

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Here's the defrost timer for your model:
WP67001036 Timer, Defrost


Its #12 here: Parts for Maytag MBB2256GES: Controls Parts

What I do is get a flathead screwdriver and turn it clockwise, there should be a small access hole under it to stick your screwdriver up in it to turn it, if your refrigerator is running when you turn it, turn it slowly till it shuts the refrigerator off, then it will be in defrost.

Give it about 20-30 minutes to see if the defrost heater comes on and defrosts it, if so, then you have a bad defrost timer.

Jake
 

solarsurf

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Jake, the drawing does not correspond with my refrigerator. I removed the enclosure on the top of my freezer compartment. I contains only the thermostat assembly, light fixture, light switch and cable/connector. The cable/connector connects to a connector at the top of the freezer compartment.

Can you tell me where the defrost timer is located on this model?
 

Jake

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Unless you gave me the wrong model#, then that drawing is what I show as yours:


Jake
 

Jake

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Wait, its in the refrigerator section, NOT freezer.:)

Jake
 

solarsurf

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Jake,
I put the freezer compartment back together then disassembled the assembly at the top/front/center of the top (refrigerator) compartment. After looking inside this assembly, I understood that you meant that the small hole access was from below, without the need to disassemble. I put it back together and then did as you suggested and turned the rotor inside the access hole clockwise. The refrigerator stopped running and it seemed that the heater came on. So probably a bad timer.

I expected that the refrigerator would stay off (since I assume that if the timer is bad, it is not spinning), however after about 30 minutes, the refrigerator turned back on. I'm going to wait to see if it frosts up again.
 

Jake

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Yes, that can happen, but if the timer has a bad spot in it, it can hang somewhere in the regular cooling cycle, thus not going into the defrost cycle.

Jake
 

solarsurf

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Jake, I let it run for a few days. It seems to be defrosting again. That is, it seems like the timer may have been "stuck". Once I advanced it manually, it seems that it is functioning again. I'm going to keep an eye on it ... I'm sure I'll revisit this problem again. Thanks for your help!
 

Jake

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Ok solarsurf, sounds good.

Jake
 

solarsurf

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Revisiting the Problem

Jake,
As expected, I'm revisiting this problem now, 8 months later. I'm now experiencing two problems. First, the top (refrigerator) compartment was not getting cool but the freezer compartment was cold. I suspected that the cause was an iced-over blower. I defrosted the unit by unplugging it for a few hours. The top compartment again was being cooled. So I suspect that the defrost timer has now failed for good.

However, now the unit runs continuously. Even with both thermostats set to the lowest setting, with both of the compartments cold, the unit runs. That is, I plugged the unit back in, allowed it to run 12 hours until both compartments we very cold. I then slowly lowered the thermostat. It did not shut off until the freezer thermostat was at off. Could it be that the freezer thermostat has failed?
 

Jake

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Yes solar, does sound like your cold control thermostat in the freezer is acting up as well, so I'd order both the defrost timer and thermostat.

Here's the freezer cold control for your model you can order:
Manufacturer's Number: 67003000



Jake
 

solarsurf

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Jake,
I've replaced the thermostat in the freezer and the defrost timer. I also found that I had to manually defrost the coils in the freezer - it was a solid block of ice. The refrigerator seemed to work OK for about a week. But it has started to run continuously. If I adjust the freezer thermostat to "Warmer", it turns off for a very short while, but then starts running again continuously. That is, it does not seem to satisfy a thermostat, even though both compartments are very cold.

I have noticed that the door at the back center of the refrigerator (it's connected to a spring) below the upper thermostat is always open. Is it possible that this thermostat has failed also?
 

Jake

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No, I wouldn't think so, is everything still cold as it should be in both sections?

Jake
 

solarsurf

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Jake,
It is cold. Everything in the freezer is frozen. Some things in the refrigerator are frozen. The coils are visibly iced over again.
 

Jake

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Its normal to have a thin layer of frost on all the coils, but is it building-up to where you can barely see the coils?

You do have your back panel ON inside your freezer right? Lots of members leave it off to see the coils easily, but thats a NO-NO, as leaving that panel off causing it not to defrost properly in the defrost cycle.

Jake
 

solarsurf

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Jake,
The ice has built up to the point where it is starting to come out of the vents. The back panel (which is on), is beginning to frost up also.

Back a week ago when I was de-icing the coils, I turned the fridge on and forced the defrost timer into the defrost phase. It did not seem that the defrost heating element was melting any ice. Is it possible that the element is bad due to the excessive icing?
 
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Jake

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Yes, you will need to unplug your refrigerator and use an ohm meter to check the heating element on Rx200 setting it should read about 30 ohms.

Jake
 

Jake

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But first check your defrost themostat.

ohm your defrost thermostat(while frosty) for continuity with refrigerator unplugged.

On these Amana's I find the defrost thermostat bad 90% of the time when your defrost heater doesn't come on.

The defrost thermostat clips on the top of your evaporator coil.

Here's the defrost thermostat for your model:
12001937 Defrost Thermostat Kit


Jake
 

solarsurf

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Jake,
I tested the defrost thermostat. I cannot get the switch to close. That is - no continuity. So this must be bad as you suspect.

I thawed the coils again. The compressor still seems to run continuously (4 hours later on the lowest setting in the freezer and fridge it is still running). Can you tell me the relationship between the upper thermostat, the lower thermostat, and the compressor? I still think it is odd that the door attached to the upper thermostat never closes. I'm guessing that the stuff in the fridge compartment will freeze again now that the coils are clear.

Can the upper thermostat cause the unit to run until the defrost timer shuts it off?
 

Jake

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Did you test the defrost thermostat while it was frosty?

Upper thermostat controls the damper, lower thermostat controls the cooling.

Can the upper thermostat cause the unit to run until the defrost timer shuts it off?
Yes, if it doesn't get satisfied with the proper temp. yet.

Jake
 
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