Okay, so I want to have a fan on my remote oil cooler come on at a certain temperature. I've got 2 temp sensors that open at (i think) 250º F and reset at 175º.

Only problem is the only thermo-switches I could buy start in the 'closed' state, then 'open' at the specified temperature. How would I wire that up with a relay so that when the thermo switch opens it supplies power to my fan?

Thanks... I'm perplexed. And even when the switch is 'closed' ... will I burn it up with power going through it all the time? Run it to a little LED or something?

Forget the thermo-switches. Hook up the fan to a switch on the dash, consol etc. When the temp starts to climb, reach over and turn on the damn fan. When the temp drops, reach over and shut the damn thing off. Keep it simple dude.
Cheers, Elliot

Do some more looking I'm sure there are temp switches that are normally open. The only other thing I can think of is a relay that breaks contact when energized. You need to get into the wiring digram of the relay to see how it works.

wire the thermo-switch to a relay:
at 175 deg, the switch is closed, so the relay is energized. Wire fan to other pole- the "relay open" position. Then when you hit 250, the switch opens and power is cut to the relay. The relay lever pops back and conects the contacts, powering the fan. This even provides a fail-safe, since if your relay or thermo swith fails, then the fan is powered.

Hey Dude
If you don't find what you need here, PM me and I will draw/scann a diagram of your wiring hook ups. Most jobber relays come with normally open and closed, 5 terminal Bosch relays are like this. 30 amp.
But I am sure someone with a PC can do it pretty quick, but I am still learning to resize pics properly, but I can help you if needed.
Regards and good luck (remember to use a "fused" curcuit.
Joe