Model Number: FRS26RC3JS3
Brand: Frigidaire
Age: More than 10 years

Frigidaire side by side refrigerator freezer. Freezer side is not freezing. Evaporator fan runs but goes slow, fast, slow, fast every few seconds. Evaporator was frosted up solid. Thawed with hair dryer. Suspect control board. Any other trouble shooting suggestions? How do I determine where control board is and confirm that it is the issue?

How do I determine part# for the control board that controls the evaporator fan?

Thank You!