New damper assembly. The fridge was not cooling. Also, light frost in the freezer but the defrost system was working. The bottom of the damper vent was plugged with ice (down next to the coil). I removed the ice plug and replaced the damper assy. I also replaced the fridge thermistor (most likely unnecessary but I did it anyway while I was in there). Everything works perfectly now. The damper was stuck in the closed position (bad motor or broken gears).