The patient: GE Profile side-by-side, about a dozen years old, no fancy
electronic controls that I am aware of

The symptoms: Nice and cold on the freezer side. Barely cooling on the
refrigerator side

Direct Cause: Poor air flow. The control damper appears open and no
connecting vents are blocked.

Previously based on reading some online advice I was given to suspecting
that the defrost system (timer, heater, kill-thermostat) may have been
faulty and allowed the evap to fill with ice and block airflow.

I finally was able to clear out all the food from the freezer side,
remove the shelves, shelf rails, and various rear covers. Bottome line
is that the evaporator is *not* plugged with ice so that was a dead end.

However I did notice that the circulating fan inside the rear of the
freezer sometimes doesn't come on when the compressor and condensor fan
do. I presume these always run together. Also sometimes it seems to
spin sluggishly.

So now I am definitely on to something. When it wasn't turning I could
get it going by giving it a push by hand.

But here is where I am still a little puzzled and may need advice:

So far as I could tell by turning it, the fan turns completely freely.
So it's not like it's bound up. It spins freely and you can feel a
little "cogging" effect from magnetic interaction. This is one of those
small induction motors where there is a single coil offset to one side in
the magnetic structure and has just a simple rotor. And you could feel
that the power was on.

So why would it not start or run sluggishly? It's getting power and it's
able to spin freely...what more is there? If friction was high I should
be able to feel it. And if power wasn't there or the coil was
intermittent that would be apparent too. I don't get this sluggish
business.

So I wonder if replacing the motor would even cure it. Before I do that
I wonder if it's not getting full voltage for some reason. As I said so
far as I know this fridge has no electronics. Could there be some
provision for regulating fan speed? This isn't the kind of motor that
you'd do that via controlling the voltage anyway. And if it's turned on
via the same thermostat switch contacts that turn on the compressor then
it can't be that some contacts somewhere are bad giving it poor voltage.

I think before I go ordering a new fan I should see if I can connect it
directly to AC and eliminate any issues with the power getting to it.

Speaking of fans I temporarily put a muffin fan inside the fridge side
under the inlet damper to pull more air in (I cable-tied it in place) so
I can maintain proper temp on that side until this is all resolved.
That's working well for now but I still need to fix this thing.