looking for experience - plugged coolant line anyone?

[Livolsi, Stephane]

Patient: 86 5KTQ

Symptom: Blower blows strongly but only cool from defrost, dash and foot
vents even with engine fully warmed up and climate control on max heat.
There is just a hint of warm coming through.  Previously would blow very hot
with engine warm.

Original diagnosis: Defective heater valve.  Exploratory surgery on heater
hoses determines that heater valve is wide open and OK, BUT when the valve
was removed from the patient, no coolant (none, nada, zip, zilch, nothing to
clean up off the floor) came out of the disconnected lines....WTF?  Blowing
in the heater hose going from the valve to the heater core (don't ask, ok?)
makes coolant come out of the heater hose that goes into the heater valve.
That means the air I blew in went all the way through the heater core, back
through the engine and then back towards the heater core through the heater
hose to the heater valve.  WTF2?

Secondary Diagnosis:  The neck on the radiator top hose connection is known
to have broken off and parts ingested into the cooling system.  The flow is
from the engine to the top of the radiator, right?, therefore the pieces
probably ended up in the rad, and into the lower rad hose, and back into the
engine and has since plugged a smaller line supplying the heater core.

Questions:
I know that the water pump runs off the timing belt, but is it possible for
the engine to be running well (which it does) and have the water pump not
pumping?  It seems to me this is impossible so must assume that the pump is
pumping if the engine is running.

Anybody experience a plugged coolant line by foreign object and where was
it?  What is the most likely suspect?

Multifunction temp switch is new this summer and gauge works well.  However,
another area of concern is that sometimes the rad fan will kick on while the
gauge still indicates relatively low temp.  Thermoswitch for fan is in lower
rad while multifunction temp switch is on the engine.  How can the rad be
hotter than the engine?

Any experience, suggestions welcome.

PS: Had the first real snowfall of the year yesterday.  One word: Quattro!

TIA

Stephane Livolsi
86 5KTQ
Williams Lake, BC, Canada