Single green/black wire coming off of blower motor?
 

http://www.rotaryheads.com/PDF/2nd_g...AC_systems.pdf

Looks like voltage supply for relay coils P. U-11,12

I believe it goes to the power transistor.

The power transistor is on the other side of the housing. The power transistor is a three terminal device, and I think it has a single 3-terminal connector. So, you might want to check the blower motor resistor since it has three connectors -- a 1-terminal, 2-terminal and 4-terminal connectors (https://www.ebay.com/itm/HVAC-Blower...7CMake%3AMazda). This 1-terminal connector is probably where your stray lead connects.

I would presume so. So let me ask, is your hanging Green/Black wire a male or female spade? The 1-terminal connector on the resistor is a male spade. Hopefully, your hanging wire is the mating female spade.

So, I'm bit confused here. In post #1, you wrote: "Single green/black wire coming off of blower motor? It’s the only wire that’s not plugged in, not sure where it goes." Than in post #7, accompanying the photo you wrote: " It’s the single G/B wire at the bottom. I have no idea what or where it connects to".

The blower motor is not in the unit that you show in your photo. The blower motor is mounted vertically under the dash next to the kick panel at the far right hand side. The blower motor has two leads, a power lead (G/B) and a ground (B). Have you traced the wires from the blower motor? The G/B wire from the blower motor must plug into the hanging G/B that you show in your photo.

So, let me start off by saying that I replaced the blower motor in my 90 GXL about a month ago (https://www.rx7club.com/2nd-generati...motor-1130016/). The blower motor has a 2-terminal plug.-- plug has two 1/4" spade connectors that are perpendicular to each other -- one is power the other is ground. This connector plugged into the dash harness.

Ok, maybe your photos deceived me because I've never completely removed my blower assembly. From what I gathered from the FSM, the resistor appears to be part of the blower assembly. After searching the web (https://www.rx7club.com/new-member-r...istor-1042684/), some people say it's part of the heater box and others say it's not clearly specified where it's located. I would suggest first checking the blower assembly for the resistor. It's probably attached to the blower assembly because it's leads look to be only a few inches in length. Sorry, I can't be of more help.