the fan temp switch screws into the bottom of the intake manifold. it gets hot and makes the ground circut. i got an adjustable fan controller from summit for 50.00 the temp sending unit screws right in to where the factory one went. made by derale . just set it with a screw driver when to kick on.
I had to replace mine on my xr4,stick a screwdriver in the hole and make sure it is not all clogged up with sediment when you have it out, sometimes it is so bad water cant get to the switch causing it not to work or come on later causing problems.