Board ASM Encoder

The fridge would go into defrost and not cool down again. Fan was still blowing. I replaced the thermostat and it worked like new for about a week and then started doing it again. On top of everyting, the schematic and parts list taped to the fridge when I got it is apparently for another model. Everything I saw on the internet said it was the Board ASM Temp Control but after ordering one I found out that this model may not even have one. Is the Board ASM Encoder the same thing and could this be the cause of the problem? How about the thermostor?