[200q20v] Overheat alarm? at 24deg?

[digital leopard]

Problem...got in the car tonight at 11pm after 16 hours at work, and was
looking forward to the drive.  After about 20 minutes of driving, including
a stop at a friends house when I left the engine running, engine coolant
alarm comes on.  Now, this is Denver, it's snowing out, and the outside temp
is 24deg, according to the car.  I pull into a station and check the coolant
tank, which seems a little low, so I fill it.  Get back on road, all seems
well, turn on heater...bang, alarm goes off.  And stops, after 2-3 min.  And
goes off.  You get the idea.

During this time, the Acutal Temp, on the Gauge, never rises more than 50%
above the first thin hashmark, well below the temp at which the fan should
come on.  And it can't be low coolant, I just filled the silly thing.

Once I'm on the highway for a short while, the alarms stop.  The temp at
this point is below the first thin hashmark.

Slow down to get off highway, get off on exit, don't even have to stop for
light...Alarm goes off.  Supress desire to put fist through dash.

Drive home, check Oil (fine) and Coolant (Fine).  Squeeze upper radiator
hose, hear gurgling noises, check coolant in overflow tank again.  It's
still fine.

OK, time for advanced trouble sensing.  Turn car on, turn AC to max, wait.
Fan comes on pretty much when it should.  Goes off (completely) shortly
thereafter, without much motion on gauge.

Turn heat to max, fan does not come on, although gauge reaches HIGHER temp
than the temp at which it came on w/AC running.

Turn Climate control off.  Gauge climbs to near first thick hashmark, fan
comes on, gauge CONTINUES TO CLIMB, and fan goes off after needle is
centered over hashmark.

It's 1am, I'm exhausted and out of ideas.  Is this, as I suspect, a bad
Multi-Function sensor?  Would that cause the screwy gauge readings as well?
Or is this something more esoteric?  The M-F (appropriate, that) TS is less
than 2 years old; should it go bad this quickly?

Thanks in advance, Ron.

>>------------------->

               "Never do an enemy a small injury."
                                --Nicolo Machiavelli


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