Kenmore 253.60082411 Refrigerator/Freezer defrost problem

[jhmod]

I have a Kenmore 253.60082411 refrigerator/freezer. I am having the following problem with this unit. Recently, I noticed frost appearing on the inside of the freezer, freezer burn on some food items and the refrigerator not nearly cold enough. The freezer was very cold. I put my hand in the back and couldn't feel much cold air coming through the vents. I emptied both the freezer and refrigerator, removed the back panel of the freezer and noticed that the hole between the refrigerator and freezer was clogged with ice. I defrosted the unit, removed the ice and everything was fine for a few days. Now, I notice the refrigerator getting warm again and frost appearing in the freezer. The coils on the inside of the freezer have a lot of white frost on them and the hole is clogged again.

This unit has some self-test ability. I was able to trigger a defrost cycle by pressing the door button 5 times. This caused a lot of water to dump into the fresh compartment.

What is likely the problem and what would be the proper way to confirm the part that is defective?

[Vance R]

Check to make sure the defrost drain is clear. Next check both door gaskets for proper sealing.

[jhmod]

Did both of those. I assume the extra water spill was due to the fact that the coils were completely frozen over. I'm less concerned with the spill than I am with the fact that I have to trigger the defroster manually. That means the heating element is fine. I'm wondering what else could be defective and how I would troubleshoot that part(s).

[Vance R]

Check the defrost thermistor resistance using the specs from the tech sheet.  If that is good it is more than likely the board.

[jhmod]

Is that the same as the bimetal thermostat? When I search for "Thermistor" in parts, I find nothing.

[Vance R]

At sears parts it is item 21a in system parts.