I bought one of those relay wiring harnesses from the dreaded discount auto parts store. What ended up happening was the diode for the AC burned up the harness, and I was left miles from home, in town, in traffic, in summer.

The temperature switch was the non-adjustable one that came with the harness. Whatever temp it was set at worked, and I kept it. I drilled and tapped the thermostat housing to accept it. It didn't come in contact with engine coolant, but it worked great. The wiring, I have written up in a fan shroud DIY. I used a dual relay set from Tyco electronics.

http://i307.photobucket.com/albums/n...laycircuit.jpg

http://i307.photobucket.com/albums/n...x-7/Relays.jpg

https://www.rx7club.com/2nd-gen-archive-72/diy-electric-fan-shroud-808292/

I'm using a temp switch out of a Starion. It's very similar to the Summit one Jack is using. My on temp might be 5deg lower. What I liked about the Starion switch is that the the thread pattern matches the OEM temp switch on the back of turbo water pump housings.

IIRC that OEM temp switch is used for an a/c electric fan..which is an option...IIRC. Regardless of the fan being an option or not. It is not on any of the verts I've owned, so maybe it's a turbo thing. I've got a 13B turbo swapped into my vert so taht switch was unused. In my case I was able to put a different switch in to an OEM spot for easy install and use.

What I did for wiring was rather than use an inline fuse I used an unused fuse link on the main fuse bank in the engine compartment. I had to use my dremel and grind down the male spade underneath because it is wider than the female spades you can buy at the store. I also had to cut off the unused portion of the harness for my female spade. I've had zero issues with it and it really helps clean up the battery wiring.

There is a thread about wiring in different thermoswitches on these forums, but I don't have time to find it ATM.

I don't remember what the pic of your engine bay looks like. But if you have removed your air pump for emissions removal you can use the same spot I did for my aftermarket temp gauge. The air pump bracket that bolts onto the water pump housing has a bolt hole drilled that sits right over the channel where the coolant travels. I took my housing to a machine shop and had them drill and tap that bolt hole. If you'd like I can post pics, just let me know.

The switch is grounded. When it makes on rise 195*, it makes to the ground. That activates the coil in the relay turning on the fan. I have another relay that activates the first relay when the A/C compressor comes on. Thus I have fan on temp rise or on compressor activation.

Works great, like OEM.

Just ordered it up!

Hose adapter with 3/8 NPT powder coat blue (to match my RB coolant hoses)
Summit racing 200 on 185 off 3/8npt thermostat switch
Was able to get the heavy duty 70amp relay at Fry's electronics last night for 8 bucks.

Thanks everyone for your help!