Hi @nick29463
Here's the [document|41368|Technical Service Guide] that may help.
Your refrigerator model series is not listed in the guide but as best as I can find out it is also applicable to your model as well.
Go to p.52 (54 of 65 pdf) to view the procedure to conduct the diagnostic tests and check if they show anything amiss, especially test 0:7 i.e ''control and sensor system self test.''
If you find the problem and it is a faulty part that needs replacing, here's a [https://www.searspartsdirect.com/model/2ry1aaxthk-000432/ge-ziss480drhss-side-by-side-refrigerator-parts|parts list] that is useful. Locate the wanted part in the list and note the ''manufacturer's part number'' that is shown with it. Search online for the part number only to find suppliers that suit you best.
Sometimes if you're lucky if you search on YouTube for ''(insert wanted part number) replacement'' there may be videos that show how to remove/replace the part.