The PO put in a manual switch under the dash to turn the radiator fan on. The fan wiring is still there, I bought a new switch connector, but I can't find the wire to connect it.
Which loom should I start looking into?

*edit* Where is the cooling fan relay? At the brake booster?

not sure about your first problem, but I heard the relay is the one to the right at the booster.

I don't know where the original wire to the switch comes from. Probably from the right hand side with the fan wiring, but I don't have a clue.

By the Brake Booster??? There are 3 relays their, but they are for the Fuel Pump, MAF Sensor Power, and MAF Burnoff. I can't think or see of any other relay there in that place!

If you want a manual switch for your fans, your probably better off removing ALL the PO's wires and starting from scratch. This way you'll know its been done right, clean, and with the proper gauged wires.

I don't want a manual switch. I want to know where to start looking for the original wire that goes to the switch.

tbi doesn't have maf

The relay you're looking for under the hood should have a heavy gauge (12-14GA) red wire (+12 bat) and a black/red (+12v fan).
There should also be a light gauge (18GA) brown/white wire (+12 switched) and a green wire (ground).
The green wire, if grounded, switches the relay, running the fan. This should be the (tapped wire for manual fan control) wire that goes to your fan switch which, normally would be in the passenger side head, unless it has been relocated.

Well, that's a start. My switch is in the thermostat housing so I figured the wire would be laying on the intake manifold. No such luck

Unless the relay has been 86'd, I would find is and trace the green wire to it's termination. Starting at the booster would be the most likely starting point. The only other the location I can think of for a fan relay is the pass side of the radiator on the support (metal)

I would say (as a guess) it runs in the harness behind the distributor (if the relay is by the booster) but, it seems to be a little different for every year/engine so, it's more guess than fact.

Ah yes, sorry, I forgot your car was TBI!

Im in the same boat as you my friend. Except my PO put in a new electric fan and ran all the wiring from the battery straight to a dash switch. I plan to dig around this weekend so Ill let you know if I have anything helpful to add after my weekend adventures. My car is a TBI as well.

Also, Deadbird thanks for the info. This will be a helpful start for me aswell.