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Author Topic: Defrost Questions For Maytag MBF1958XEW  (Read 127 times)

Offline PGB1

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  • Member Since: May 2015
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Defrost Questions For Maytag MBF1958XEW
« on: July 24, 2019, 05:04:10 AM »

Hello All!
We have a Maytag MBF1958XEW Bottom Freezer refrigerator which we purchased new in 2010.
For the last many years, we've had an occasional problem with warm refrigerator compartment temperatures. It will happen perhaps twice in one week, or only once in 2 or 3 months. Unfortunately we don't notice until the box is in the 60-F range, so the food must be ditched. The frozen food is still frozen.

Finally today we have decided "Fix It or Ditch It".

When we notice the refrigerator compartment is warm, I look through the grill in the freezer compartment and the evaporator is covered by thick frosty ice. Sometimes the fan shroud in the refrigerator compartment has a very light coating frost on it.

The Tech Sheet (W10308623) shows how to force defrost, but that test has never worked, so we do an alternative test:
We put the unit into a short defrost by putting the board into "Service Test Mode" and selecting "Test One: Defrost Thermostat & Defrost Circuit Test".  This gives a 9 minute defrost cycle. We repeat until the display shows the defrost terminator disc is open, indicating the evaporator is warm (ice gone). It usually takes a dozen or more 9 minute cycles before the defrost terminator opens. (The status of the terminator is shown on the display as "S" or "O". "O" means warm & open disc.) Then the unit runs fine & eventually reaches set point temperature (usually several hours).

Also note at that time, I also clean the condenser coils. Usually they have a good coating of lint, sometimes to the point of blocking the front row.
I blow it out with compressed air from the back and front, then vacuum the area. (Access from the back is nearly impossible due to component arrangement and a solid wall in the unit, so I have to primarily try to force the lint through all the rows of fin tube and out the back.)

My questions are:
A) Could the dirty condenser be the cause of the unit not defrosting, or should we focus on replacing the Jazz board as the culprit?

B) The amount of time between when the unit fails to cool, needing manual defrost, varies- Does this point us to the Jazz board as defective?

C) The tech sheet shows that the defrost cycle can be changed from "Adaptive Defrost Time" to "Fixed Defrost Time".
    Does this mean changing it will force the unit into defrost every "X" amount of hours for "X" number of minutes?
    Is this a good option to try for solving this problem?

D) I recently put a loosely woven filter fabric on the inside of the kick plate grill to help slow the build up of dust and lint on the condenser coil. It helps, but does
    not solve the problem. It does make cleaning easier.
    Am I causing any problems doing this?

Thank You All very much for sharing your knowledge and expertise. I'm trying to avoid spending on a new Jazz board if it will not solve the problem, so I thought it wold be wise to ask here.

Enjoy Today!
Paul

Offline manden

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  • Member Since: Oct 2011
  • Posts: 266
Re: Defrost Questions For Maytag MBF1958XEW
« Reply #1 on: July 24, 2019, 07:32:26 AM »
Search the forum for " MBF1958" a couple posts come up.
Looking at them it seems defrost is a fairly common problem with these units.

A) Could the dirty condenser be the cause of the unit not defrosting, or should we focus on replacing the Jazz board as the culprit?
No

B) The amount of time between when the unit fails to cool, needing manual defrost, varies- Does this point us to the Jazz board as defective?
Yes see the other posts.

C) The tech sheet shows that the defrost cycle can be changed from "Adaptive Defrost Time" to "Fixed Defrost Time".
    Does this mean changing it will force the unit into defrost every "X" amount of hours for "X" number of minutes?
Yes , every 6 hours but I do not know how long the defrost cycle lasts.
    Is this a good option to try for solving this problem?
It is worth a try but you will probably using more electricity in fixed mode.

D) I recently put a loosely woven filter fabric on the inside of the kick plate grill to help slow the build up of dust and lint on the condenser coil. It helps, but does
    not solve the problem. It does make cleaning easier.

    Am I causing any problems doing this?
It should not cause a problem as long as you clean it regularly.
You could check it by checking the air output with and without it to see if it significantly reduces air flow.
I think your unit draws air in through the kick plate and out the back.
My unit draws air in half the kick plate and out the other half.
I used some furnace air filter material and have not noticed and problems.


Offline PGB1

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  • Member Since: May 2015
  • Posts: 7
Re: Defrost Questions For Maytag MBF1958XEW
« Reply #2 on: July 24, 2019, 08:05:05 AM »
Thank You Very Much, Manden for sharing your knowledge about the topic.

For some reason, before I posted my question, I didn't find the posts about the Jazz board. Thanks for the idea to search, as now the posts came up.
It seems we are not the only ones with Jazz board problems.

That's a good point you made about timed defrost & electricity use. I guess it is like going back to the old-timey (and some current commercial) refrigerators with the mechanical timers for defrost control. Our last refrigerator had a mechanical timer and was 42 years old when we found a new home for it. We owned it for about 25 of those 42 and only put one part in it- coincidentally a defrost terminator.  (Wonder if it is still running?)

Several years ago, I thought about changing the board as a "If I can't figure it out, I'll put in new parts" method of diagnosis. But the prices were over 200.00 for a replacement. They sure have come down- Today I found some aftermarket with 1 year warranty at about 50.00.

Thank You Again for helping us out with this situation. I think it is time to try a new Jazz board.

Enjoy This Day!
Paul