Just got a new fridge which uses the commonly available "Jazz" PCB to control the hardware. Purchased an extra board just for grins and worked out the schematic. It uses a Microchip PIC16F916 and it runs off the 120VAC mains un-isolated. Generates a 5V supply internally for the controller, and a 24V supply to drive a couple of relay coils.
Even though none of the circuitry is isolated from the AC mains, it lives behind a plastic panel and can't be touched by the user...so I guess that's what got them UL approval.
Anyway, I was thinking about doing an AVR-based replacement design. The tech sheet for the fridge pretty much explains how the firmware works so it shouldn't be too hard write some code for it.
Anybody interested in a copy of the schematic?