So before anybody says "this is a bad idea, it'll run to hot, or your going to wreck your engine" I have an adjustable thermostatic switch in the mail that I plan to use, I just want your opinion on the subject. so here it is, will this work.

the stock switch operates at 207f and breaks the circuit. The relay will then go to the off position and provide current to the electrical fan.

 

So, assuming you drew the relay diagram correctly, does your switch *open* at selected temp.? This is very well possible, but may not be the case.

If the thermo switch *closes* (continuity) at a user-selectable temp., then you need the fan connected to the side which closes when power goes through the relay coil side of the relay.

I've just drawn a pic. in paint. WARNING - I'm not an artist!

BTW, add a fuse on the power side if tapping from the battery. Also, if you have no stock belt driven fan, I'd set the fan to go off lower than 20* something.

 

that is how I had it displayed. And it is a stock unit that can not be adjusted which is why I am not going to use it.

 

went ahead and tried it and it works well. Fan comes on evey couple minutes and stays on for 30 seconds or so. the fan is pulling about 200watts. one issue that came up was that the solenoid is always engaged when the key is off. On the plus side if the sensor or wire fails the fan will default to the on setting.