Adding ac wiring

[Anthi4078]

Hey I’m working on adding all the wires needed for ac into my trucks harness. I’m having a very mind boggling issue with one of the wires from the clutch relay. So on my donor Cherokee harness (1988) the blue/white wire come out of the relay and goes into a 10 pin connector near the diagnostic port. However on my truck (1987) there is already a blue/white wire there and it runs all the way from the bulkhead connector (C100) to the one above the engine (C101). I can’t find a blue/white wire anywhere in the wiring diagrams other than for the clutch relay to the ECM. If anyone knows what this wire is for that would be appreciated or how to add the ac wiring to it

[Anthi4078]

Hey so I I think I might be figuring out parts of the puzzle, or I’m way off but there has been this 4 pin weatherpak connector up by the washer fluid bottle that I’ve wondered what it did for a while now and I was down there looking for wiring for the electric fan and just noticed that the mysterious plug also has this pesky blue/white wire. Then I noticed that it also has two light greens and a orange and those seem to be all the colours I'm messing with for ac. So I’m thinking maybe that plug is there for maybe the dealer added ac so they could just put all the wiring in and plug it in there and not have to mess with the bulk connector. Hopefully it’s that simple since I didn’t really want to have to try and depin/repin that monster connector 

[Ωhm]

4.0L Option: