In May I started having a problem with my Maytag Wide by Side, the frig side kept getting warmer. I took off the panel in the back of the freezer and the cooling coils were frozen so no air could move around them. I ordered the replacement Adaptive Defrost Board and the Heater and therm. assy. I installed both and the unit work wonderfully until early Sept. Same problem. Appliance Parts Pros send me a new defroster board but before I put it in I wanted to check the heater, along with the thermostate attached to it. I unpluged the unit from power and then unplugged the harness and tested to see if the thermostate was open or closed when it was cold, it was open. I took it then still in the freezer and dipped it into warm water thing there should be some continuity. The ohm meter does not change if it's warm or cold.....shouldn't it? I test between the black and white and it's connected but when I test across the two white wires of the thermostat there is no change warm or cold. Do I have a bad thermostate?

Tom