Tell me how you wired yours please?  Pics of how you routed the wires if you have them available.

 Are you happy with them? Any overheating problems?

Jim,

I've actually got the wiring diagram from Dewitts. It tells me to hook them to certain types of circuits and I understand that, my biggest question I guess is where do I hook the "Ignition" wire.  I have the dual fan w A/C and temp sender set up, I'll hook both of the grays to the sensor along with my normal gauge wire. Ground is gonna go to the frame and the Red Battery wire will probably be on the back of the Alternator since it's convenient. 

I recommend a relay for each fan even if they are run parallel.  There should be a ground for each fan and another ground from the relays.  A 12 volt source wire, temperature sending unit wire and an ignition wire.  If you don't connect it this way, the fans will run as long as the coolant in the block is above the shut off value and your battery has power.  Without the water pump moving coolant, the fans will stay on for quite awhile even though the coolant in the radiator is below the temp sender value.  You can use a radiator probe to control the on/off values.  Everything depend on the system and application.

  Im ran my power wires to the Battery. If Your Using Two fans and Two relay's then You can set them up to come on at diffrent Temps. Many Cars are setup this way only Run one Fan as thats all thats needed. However C3's don't fit this catagory. But if they don't start and stop togeather then it dosn't put such a big surge on the Electrical System. Mine are controled by a Accell gen 7 ECU but thats another story. Richard....

I've got it all hooked up except two wires. Those need to go to an ignition circuit. I ran the battery wires to the back of the alternator and the rest were stright forward, they hooked into the SPAL fans from the relays.

Any thoughts on a good place underhood to splice into an ignition powered  circuit?

Anyone?  Bueller ?  Anyone?

you could run them on a live circuit . they will stay on after you shut off car but it shouldn't be that long to hurt anything. had a rabbit that had an electric fan and that's how they were wired. when i wire mine in i am going to do it this way.

I've got it all hooked up right but the fans aren't coming on via the sensor in the block and my gauge wasn't moving either. I put my old sensor in the intake and the gauge moved and one of the fans comes on.  What are the chances I got a bad sensor out of the box?  I can also ground the fan wires and they will come on....

 Thoughts !

jim...when you install the new sensor make sure not to usee too much teflon tape or sealant. spal recommends the least amount possible. if fans don't come on try touching a ground wire to the body of the sensor. if fans start up then it is a grounding problem. if they don't you may very well have gotten a bad sensor.