Do you have frost build up on the back freezer wall? If so you have a defrost problem. You will need to test the defrost thermostat and heater. They should read closed or 0 for continuity when cold. If they test good then you need to change the control board. Also check and see if the evaporator fan is running. If not, this can cause the cooling problem as well. Here are the links for these parts. Hope this helps.
Part number: AP4299920 
Part number: AP3756388 
Part number: AP3950825 
Part number: AP2988898 