Adaptive defrost control board

[bluegrill]

I have an Amana bottom freezer model ARB2217C. The few weeks ago the freezer frosted up and the fridge section got warm. I defrosted the freezer with a hair dryer and everything seemed to work. I would see a little frost form on the back of the freezer and then the next day it would be gone. I thought this was proof that the defrost heater was working and maybe the problem was just a one time fluke. Then the same thing happened. Diehard DIY-er that I am I went on Appliancepartspros.com, looked at the parts diagram and ordered a defrost timer, an adaptive defrost control board and a defrost heater thinking I might as well replace them all while I had the unit shut down. When I took out the panel where the defrost timer is located I was surprised to find that there is no adaptive control board in there. Is it located somewhere else, or are there some units with a timer and some with a circuit board?
I replaced the timer anyway, manualy turned the timer till it clicked, compressor shut off, and there was no sign of melting frost. Tried the cycle 5 times but no sign that the heater is coming on.
Does this unit need a adaptive control board? Where is it located? Any ideas?

[Jake]

On your model it only shows to have a defrost timer not the adaptive defrost control board.

If you have a volt/ohm meter, ohm your defrost thermostat(while frosty) for continuity with refrigerator unplugged.

On these Amana's I find the defrost thermostat bad 90% of the time when your evaporator coil is frosted-up and the defrost heater doesn't come on.

The defrost thermostat clips on the top of your evaporator coil.

Here's the defrost thermostat for your model:
Manufacturer part number 12001937 is RepairClinic item number 1023500
12001937

Let me know what you find.

Jake