Refridgerator Freezer works fine -- Fridge side not cold enough.

That can be due to several problems but usually because the air from the freezer side can't make it over to the fridge side. If the defrost cycle is not working the freezer coils will freeze solid and no air flow over them to make it to the other side. Or the fan that blows the air over the coils is out. Or the damper that lets the air into the other side is not working. Or the t-stat the controls the damper isn't working, etc. Lots of things to look for but here's a few hints.

If the freezer side is cold just on the bottom but not so much on the top suspect the coil froze up (no defrost cycle working). Sometimes you'll see lots of snow type ice on the back lower wall (dead give a way). You can listen to see if you hear the fan running about in the middle of the freezer compartment (the fail quite often). You can try and find the damper "window" (will be high up near the top) between the two compartments and see if it's fully open, also the "return air" (will be low near the bottom) is blocked (loaf of bread, etc.). Lots to look for but concentrate on why the air isn't making it to the other side. Let me know if you need further help with testing depending on what you find.