that runs from the AC seceltor switch to the ignition switch?  Is that the wire that starts a spinnin my blower motor every time I puts the key in the run position??

The brown wire comes from the fuse box...or at least, it's supposed to! Sounds like "Bubba" done been there...

The fan switch should have two orange wires, one goes to the blower motor, the other to the heater resister, mounted in the A/C plenum, under the hood.
The brown wire is power from the fuse box.
The blue, and yellow wires also go to the heater resistor...this is what gives you the low, med, and med/high blower speeds.
Does the brown wire look like it ain't supposed to be on the ign. switch connector, as in, someone spliced it in?

I see NO brown wires coming from, or going to the ign. switch...

What speed does the fan run when you turn the key on? If it is slow/low, your fan switch may have problems. The fan on A/C cars should be OFF if the switch is in the off position. I think the blower does run on low on the non-A/C cars, regardless of the switch position. Adams' Apple2007-11-12 22:04:45

AC What in world is that..... sorry Paul I couldn't resist!

I don't have the diagrams here, but it sounds like we have different diagrams. If you have the factory service manual diagram, then it is prolly more correct. The one I looked at last nite only showed one brn wire. I'll check again when I gits home this eve.
The only blower relay I'm aware of is the high speed relay, which only comes into play when "high" is selected.
If your car was originally built with A/C, the fan switch should have 4 positions, one of them being "Off". Your fan switch may be bad, causing the continuous operation of the blower at low speed. There are other possibilities, but that would be the most common.

[QUOTE=Adams' Apple]...I think the blower does run on low on the non-A/C cars, regardless of the switch position.... [/QUOTE]

Part of the "Astro Ventilation"

For what it's worth, on my '73 L-48, a brown wire powers the Dukes of Hazard Hood Intake flap panel when you floor it (guess they figured the 190HP 350 needed ALL the help it could get back then 😄).

So, the brown wire seems to be a 12vdc supplier (not necessarily Common) to a number of circuits. 

It wasn't exactly a Burn Job, but I rewired the Main Harness on this car, finding wires with melted insulation throughout. Was fun though; far easier than that of an A-6. 😉

Steve