Need some help with ST 20v - limp mode

[Rulez]

My car is currently in limp mode. I have a 1990 Celica with a ST swap. There is no AC in the car. When I turn the ignition on, the fan is constantly running. When I unplug the fan, it comes out of limp mode and runs fine. I read somewhere that the ECU may think the AC is on, or that there is a problem with the AC, when the AC is not present. The harness for the AC is not plugged in and is just dangling in the engine bay (see pics).

Do I need to ground this harness? There is only 1 wire going to it which seems odd. This is driving me insane.

Any help is appreciated.

[Rulez]

UPDATE: I unplugged the o2 sensor and it runs fine. Maybe I have the wrong one?

Anyone know what o2 sensor I need for this? What a compatible car would be (4Runner I think?)

I feel like I may have the pinout wrong for the 02 sensor. Can anyone confirm this is correct?

The way I have it now:

o2 white -> brown engine
o2 blue -> white engine
o2 black -> pink/red engine
o2 black -> black engine