You're a genius Bob.
I followed most of your steps late Sunday and the fresh food section began
cooling again late that night.
This morning with a minor tweak to the fresh food temp control the
temperature was back to normal range. (I have a frig thermometer in the
fresh food section.)
Finally, it was a rather hot humid day (at least by San Diego standards)
when this all started.
I will archive your post for future reference.
If the freezer section is getting down to zero, then the compressor is
working properly. You have a blockage between the freezer and the
main refrigerator. Is the refrigerator below the freezer compartment,
that is the normal setup. You must defrost the entire freezer-
refrigerator, leave it off for at least 12 hours, and then turn it
back on. set both controls to mid-range and let the thing run for at
least 12 hours to start to stabilize temperatures. Then adjust the
controls a little at a time, no more than 105 of the range change
each time, then wait 4 or 5 hours for things to stabilize. You must
also find the defrost timer, that is probably the source of your air-
flow blockage, if it doesn't run and defrost for at least 1/2 hour
everyday, the frost will build up and block the air flow. IT is most
commonly a problem on hot damp days when there is the most frost
buildup on the cooling coils, wherever they are.