I had a spare thermo switch of unknown condition and I plugged it in
the hole quickly, then with ignition on, used my heat gun to slowly
bring the brass part of the thermo switch upward in temp.  The low
speed should kick in first and shortly after the high speed. Yeah,
it's pretty shade tree, but it got me the info I needed(the switch did fine)

Good luck

DM&FS

At 08:13 AM 11/4/2005, George Goff wrote:
>In a message dated 11/4/05 5:36:02 AM, BOBMACDOWELL@WEBTV.NET writes:
>
><< I think it's the fan switch in the radiator that's bad but i need a way to
>test it. Anybody know >>
>
>Bob,
>
>To proof out the fan motor itself, pull the red conductor from the radiator
>fan resistor and feed 12 V. into it.  To single out the thermoswitch and to
>check the fan motor along with the other cooling fan circuit
>components, pull the
>connector from the radiator thermoswitch and jumper from the black to the
>red/white conductors and then from the black to the red/blue.  If it is the
>thermoswitch that's hinky, you'll get both fan speeds with the jumpers.
>
>George