Never had this problem. If the fridge "shuts off" and quits cooling in both freezer and fridge I suspect a bad relay or possibly a compressor overheating and tripping a thermal switch. Usually once the compressor starts failing they don't get better but a bad thermal switch *might be the problem.
If it was an evap fan problem I would suspect the freezer to be fine and only the fridge getting warm.
Just a suggestion:
She is 15 yrs old, long in the tooth, and probably quite the energy hog at this point. A mini fridge keeps beer 37*F all day and uses very little electricity to get there. You can find one for about $120 new and that is what I keep stocked in the studio/man cave.
https://www.lowes.com/pd/Arctic-Fresh-2-7-Cu-Ft-Compact-Refrigerator-Black/1000903390