Hi @karl74482
Here's the [document|32672|mini manual] for the refrigerator.
Run the service diagnostic tests as described by the manual, initially for all the relevant, designated ***''FF''*** thermistors, dampers and the fan, shown in the test list e.g. 0024, 0025, 0044, 0045, 0046, 0047 and check if they're all OK or not. ''Note:'' FF = refrigerator, FZ = freezer.
If you find a faulty component, here's the [https://www.searspartsdirect.com/model/momqeme6du-000432/ge-pfe28kskess-bottom-mount-refrigerator-parts|parts list]. Scroll through the list to find the wanted part. It will have the ''manufacturer's part number'' listed with it. Search online for the part number, to find suppliers that suit you best.