Ric says:
 
> By using a combination of parts fiche, parts listing
> and other stuff I found that in the circuit is the
> temp switch, the relays and then some sort of
> ballast resistor for low speed and high speed operation
> of the fan. I believe that these resistors
> are dead. 
> 
> There seems to be, however, a "fail safe" fan switch
> somewhere which kicks the fan into high at temps
> above 230F. However, this only works with the 
> key in the "on" position.
> 

Ric:
I know this sounds *really* basic, almost to the point of insulting 
but DO check the fuse for the fan circuit.  i dealt with overheating 
on my '85 for a couple weeks, condemming the ballast resistors, rad 
sw. etc.  it be the fuse.  even with the fuse blown, the fan would 
come on when the AC switch was on.  however, your reasoning also does 
seem to fit so....  good luck!

-dan