Rad fan dosen't run after engine off !

[ang@indiana.edu]

Dear AUDI enthusiasts,


I have a problem with my 87 5kcst radiator fan doesn't run after the 
engine turn off, even in very high temp, I know there is a thermoswitch where 
located in the upper radiator hose inlet, it's a two pin type, to control the 
radiator fan after the egnine turn off. I short those two wires when I 
unplug it from that thermoswitch, the fan works immediately. Therefore I 
suspect the thermoswitch may broken, also I've tried to measure the 
resistance between two pins of the thermoswitch but there is always 0 at any 
temperature. I checked it out at dealer about this thing, they have only two 
kinds, one is black and one is red, I've tried both but both doesn't work. 
Both of the thermoswitch's PN are different from the one come with my car. 

I found this problem after my mechanic, in SF, fixed the noise that come 
from the 1st stage rad cool fan relay, I suspect that he may changed 
the original one and put in an old/bad one, so the relay won't makes any 
noise because no more current pass through the relay. This is only my own 
guess! 

Under this kind of circumstance, I really don't know what is the real PN 
for this thermoswitch. "Could anyone be kind to send me the PN or any 
information about this thermoswitch." I pretty sure the problem is come 
from the thermoswitch, if you guys have any idea about this I really want to 
listen about it.
  
Thank You

Albert Ng
ang@indiana.edu