Hello all--

Two questions for the Wire Wizards on this forum, concerning my '78:

- There are two wires attached to an electrical plug connection on the top
of the AC compressor. One is green, and disappears into a loom. The
other is black--and this one's been cut, so I have no idea where it's
supposed to terminate. I see a "ring" connector attached to a bolt on the
compressor bracket, with no wire inserted into the ring's barrel--so I'm
wondering if this is a ground, and the black wire is supposed to attach
there?

Second problem--and this one's a real mystery. On the passenger side, at
the right rear corner of the engine bay, coming out of a loom that runs
along the firewall, is a yellow wire that's also been cut--and I see no point
anywhere in the vicinity that it might be designed to connect to. In fact,
I'll be damned if I can actually see any wire inside the yellow insulation at
all!

If anybody can shed any light on these two items, it'd be much
appreciated. Thanks in advance--

Yes the black wire does indeed go to the grommet for the ground from the compressor clutch.  The green is the power wire through the compressor controls.

Are you sure the yellow wire is a wire?  It may be an vacuum line that once went to a heater hose cut off to prevent water flow with the A/C on.  Take a close look and be sure it's a wire.

Yup, Ken's right(again!) on the wires for the compressor.
And....since you have a '78, it should have a "heater control valve", or "shut-off" valve down by the A/C casing. If someone has removed it, the vaccuum is no longer needed, but it should be plugged to prevent a vac. "leak" at that point.
If the valve is still there, then you should be able to see if there is a vac. line going to it or not. If there is no hose/line on it, you've found it!!

Ken & Joel--

Many thanks for your fast replies. Any suggestions on how best to replace
the cut black ground wire? I haven't attempted yet to pull the plug-in
connection on the compressor out, much less scope out how to insert a
new black ground lead to it once I do have it out. So any ideas from you
guys--or others--on how to do that without damaging the plug would
also be much appreciated. (I assume it just pulls out--but I'm also sure
these connections must get brittle from age and heat, so I want to be
careful with it).

As to the strange yellow wire, nope--it's definitely not a vacuum line. It's
literally the diameter of a standard electrical wire (only a slightly larger
gauge than most of the rest of the car's wiring)--and it comes out of one
of the looms. The puzzling part is that I can't see any actual wire inside
the yellow insulation, as you normally would. I didn't cut it open yet, so I
guess it's possible that the end has become fused over from the engine's
heat, masking the wire inside. That's the only thing that makes sense to
me. And where it's supposed to go, and what it's supposed to do, is really
a mystery (I've ordered a wiring diagram, but don't know if that's really
going to help me figure this one out or not!)

Can you post a pic of this mystery "wire"?

Joel--

Here's the link to my best shot; hope it helps you shed some light (pardon
the bad pun) on this weird 'wire':

UnknownWire.jpg">

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Sorry, Joel--I've tried to figure out how to post an image on this forum,
without success. And then I tried to post the above link to the image--
with similar lack of success. Now I'm stumped as to how to show you this
picture!SFVette38864.6834259259

I have sent SFvette a pm...I can only find one yellow wire under the hood on a '78. It is for the heater resistor.Adams' Apple38865.7491550926

Otay, folks...here's a pic of SFVette's MYSTERY WIRE!!!
It still looks like a vac. line to me, but...what does anyone else have on this one?
I can find only one yellow wire under the hood on a '78 diagram, and it goes to the heater resistor. It appears, in the pic, that all the wires that should be are connected to the resistor. I'll attempt to enlarge the pic, and see if it gets any clearer.
Don't be afraid, ya'll...jump on in with your idiers!!!Adams' Apple38865.7509722222

My 79 has a "yeller" wire going to the alarm system horn...

Well, of course it do, Jim!!! But...is your alarm horn under the hood, by the A/C system?