SubZero Model 632 not cooling

I have a 12~13 year old (2005) SubZero 632 Fridge that is not cooling well. The freezer works fine and there are no error codes. The fridge is set at 34 deg F but that actual temp is between 40~45 Deg F. About a year ago the fan stopped working so I replaced it and the fridge worked find till recently.

I don’t know much about the fridge as it came with the house I just moved into. I’m hoping it is just a thermostat replacement or something simple that I can do myself (fingers crossed)

Hard to find do it yourself info on Subzero 632 so Any help would be appreciated!

Thanks,

B