With an 87 or later Vanagon, here is the lowdown....

The a/c wires that we have to deal with when converting to subaru power are all located in the left side of the engine compartment and are extending out of the d pillar area behind the left rear wheel.  You'll see a single black wire conduit run holding three wires.  One large gauge red, One Red/Blue wire, and one Brown wire.

If you have your Bentley manual handy - I am referring to page 97.140 and 97.141

The Red wire with the eye on it should go to the post in the black junction box - Bentley shows a 50A fuse in series.  The fuses are located up in the subpanel up in the dpillar area on the left side of the van.

The Red/Blue wire is the one coming from the Compressor Clutch relay and the connector is T2f. 
Subaru ECU Wire C9 is to be connected to this Red/Blue wire and also to the Subaru A/C Compressor Clutch wire.
The extra Red/Black wire with the single pin connector on it would have gone to the Idle stabilizer on your old WBS engine.  It can be cut off or wrapped in place.

The Brown goes to ground. I usually route it to the body ground connection located in the engine bay on the left side.

The Kep instructions are correct:
- splice the Yl/Gn wire from pin 1 on the A/C compressor connector to the Bl/Rd wire from C9 and take that to your Bk junction box.
This wire gets connected to the old Vanagon compressor clutch wire - I do not have my bentley at home to night - but maybe you could look that up - I have forgotten where it is located.

All the best,
Tom Shiels


***To summarize:  The vanagon Red/Blue wire from the left side of the vanagon engine bay should run into the black junction box.
The Yellow/Green wire from pin 1 of the subaru A/C compressor connector should run into the black junction box.
Splice these two wires and route them to the Subaru ECU Pin C9.