I have a kenmore upright frost free freezer mod #253.26432100. A couple of months ago everything defrosted and the unit was not running at all. I unplugged it cleaned it and plugged it back in, it turned on and seemed ok. We have been using it since. Last night it did the same thing, everything defrosted and the unit was not running. We cleaned it out, and when I plugged it back in the compressor came on and the unit is running fine. We did not have any loss of power at either scenario. Why is my unit shutting down? Is there some type of overload that only resets when unplugging unit?

You have a problem with the ADC.

Frigidaire has also jumped into the market with an adaptive defrost board. The fresh food section light switch and light bulb must work. To initiate a defrost cycle, open the door and push the light switch in and out 5 times within 6 seconds. The compressor and fans should shut off and the defrost heater should come on. Open the door and push the light switch in and out 5 times within 6 seconds to remove the refrigerator from the defrost mode and back into a cooling mode.

This product comes equipped with an Adaptive Defrost Control (ADC). To activate manual defrost, press and hold the Freezer temperature UP (WARMER) key while pressing the Fresh Food temperature DOWN (COLDER) key 5 times within 6 seconds. A "d" in the freezer temperature window and "F" in the refrigerator temperature window will display when the heater is activated. To deactivate manual defrost, press and hold Freezer temperature UP (WARMER) key while pressing the Fresh Food temperature DOWN (COLDER) key 5 times within 6 seconds. "d" and "F" will be displayed until the defrost cycle is complete. (approx. 8 minutes)