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.