Yes, I'll keep an eye on it. The freezer is at -21 now. Probably because it has not been open all day. Thanks for the specs on the thermistor. At first glance, there does not appear to be much more ice than what I noted yesterday after it had been running for about 6 hours. Perhaps that was due to condensation, as I dont see how it would have hit a defrost cycle so early.

Well, my heater must be trying to work, because my wife just said she opened the freezer and heard a sizzling noise. When I looked back there, I could see the water dripping down from the defrost cycle and hitting the heater wires laying in the pan and sizzling, so it is keeping it open. I just think the freezer is so cold, its trying to freeze before it can get down the tube. Not blocked yet, as I can hear it draining into the pan. I'll check the thermistor this weekend. If the thermistor is good, did you say the controller board would be the other possible item? Thanks again Simon.

Understood. I went ahead and ordered the thermistor just to have it on hand since it was a cheap enough part. I'll dig into it once I get the new part and report back.

Where exactly is the thermistor located? Is it near the damper assy in the top left portion of the fridge?
Thanks again!

HI Simon,
I received the new part today. I have not yet put it in, but I did research and learned how to put the fridge into diagnostic mode. It has a specific test for the Freezer Compartment thermistor and it says that it passed. That being said, I have had issues with the Ice Accelerator button on the control panel where it will begin randomly beeping on/off all by itself. Sometimes pressing the button a bunch of times will make it stop. When it gets in that mode, none of the other buttons will work (I think the switch is getting stuck in the closed position). I was tempted to pull the board out and try and clean that switch with some electronics cleaner. I also wanted to check its behavior with a meter and see if it is truly getting stuck in the closed position. If it is, I'm half tempted to just unsolder that switch from the board since we never use it. The manual says this button will drop the freezer temp to -10 or so. Could this switch be the cause of my issue? Thanks again. Craig

Well, I pulled the board, and although I could not really confirm that the switch was bad, I went ahead and pulled it from the board. Operation still seems to be the same with the freezer at -15 or so, and the fridge at 37 (set temp). But at least it has not been beeping at me ;) I will go ahead and replace the freezer thermistor even though the test says its okay just as a precaution. If that's not it, there must be a problem with the board itself. I wish I had the schematic for that circuit card, as its probably just one small component gone bad.
I'll report back after I replace the thermistor.