Is the evaporator fan in the freezer running. It blows cold air into the fridge side through a damper in the wall between the freezer and fridge. Make sure the damper is open.
Below the evaporator fan is the evaporator coils. Remove the back cover in the freezer to observe the frost pattern. stopped up? clear? ice in one spot . frost everywhere. | 
Frig not cooling Freezer ok 
