Frost build up

Hi. This unit has an evaporator in the fresh food section. It sounds like this is where your frost build up may be coming from. How are your temperatures in the refrigerator section? Frost build up isolated to the evaporator cover usually indicates that it is not self defrosting. Your model has a service pointer that may be your issue. Take a look at the link I have attached. See if the serial number of your unit falls with in the serial range for the pointer. I have also attached the tech sheet on this unit so you can run the diagnostic tests.