Evaporator Coils iced (refrigerator not cooling)

Side-by-side GE Refrigerator is only cooling to 50 degrees, freezer to 10 degrees. I took off the inside panel in back of freezer, and the evaporator coils are completely iced over.

I took the panel off after I looked in the inside/back of the freezer and noticed a green wire with a clip on the end, that was hanging loose on the inside back of the freezer part. I can’t see anyplace where it should be connected - but then everything is iced pretty heavily. If this is a ground wire, it may just have clipped to the metal frame someplace?

Also, almost since the unit was new (came with the house), the refrigerator "moans" loudly for 10-20 minutes at a time - that noise has now ceased. I wonder if that is a circuit board?

Thanks for any advice.