Water line froze, food in fridge started freezing

I knew almost as soon as I found the frozen milk that the air-flow diverter, whatever it's called, had broken. It's a plastic part that opens and closes to allow cold air from the freezer into the fridge side.

Step one: clear off the top two shelves and take them out.

Step two: remove the lower piece of the assembly. It pops straight out at the top and drops down after that. If you pull the bottom straight out, you may break the bits that holds it to the fridge wall.

Step three: remove screws holding in light, and then the screws holding in the AASM COVER FF INLET K (wish I had a better name for it).

Step Four: Unplug the unit from the fridge wall.

Installation, reverse, except maybe unplug the unit earlier.