'84 5kS Fan

[Michael Spiers <mikes@specnet.com>]

OK, so I'm driving home last night in my (her, whatever) 84 5kS.  There is a
large leak in the radiator, so I think most of the coolant drained out of the
thing sitting in traffic on the beltway.  I get off the beltway and am sitting
at a light, all of a sudden billows of white smoke pour out of the front end of
the thing.  Pull over, just steam from the holes in the radiator.  However, the
temp gauge is getting high, so I drive till I find a school I can fill up the
radiator jug with.  By this time, the temp gauge is getting kinda high.  Get
out and pop the hood, the damn fan isn't even on!  I know that thing works, it
always runs at a low rate whenever the ignition is on, and kicks in louder when
sitting in traffic and temp gets higher.  I'm guessing that when the car is
running and the fan is barely moving, that's stage I.  When I hear it kick in
in traffic, that's stage II.  Does this mean the stage III in this heap doesn't
work?  As soon as the car cooled down to normal operating temps, the fan worked
just like it normally does.  The fact that the thing wasn't even running when
it was overheating kinda annoys me.  How do I troubleshoot a busted Stage III?
 (Oh yeah, BTW, if your Audi is overheating, DO NOT turn on the heater.  I did
this as a hope to get the heat from the motor and into the car, and cracked the
heater control valve right in two, dumping the remaining coolant all over the
transmission and the school parking lot.  A piece of copper tubing got the car
home.)  Help!  TIA for any suggestons.

-Mike
87 5000CS TQ