Not sure where this wire is sorry.
The A/C compressor clutch supply wire runs from the front of the
compressor to a detachable, single pole connector. The wire
is usually black. You can trace the wire by hand if it's can't be seen.
By interrupting the A/C clutch electrical supply the compressor won't be
able to engage, only the left condenser fan will start, after you
turn on the A/C. If the idle is not raising in this case then it's a problem.
What I couldn't find is any connections coming off the vacuum pipes. I believe this is required for the idle raiser no?
Yes, there should be a three way solenoid valve which passes
extra depression from the brake servo vacuum pipe to the
ignition distributor's pneumatic advance chamber.
If this solenoid is missing, the normal idle RPM can't be maintained when
the compressor is engaged.
I hope this is helpful.