an adapter kit that can properly regulate the fridge temperature when tempuratures drop down to 40 degrees F.

I've been fortunate, my garage fridge stays frozen in the freezer and just really cold in the fridge (although the top shelf on the left side will freeze milk). The rest of that shelf and the other shelves don't have a problem with freezing.

When we've had a warm winter, the freezer actually didn't do well in keeping stuff frozen.