Thanks Nick, you are a legend. Really appreciate it.
Last question, when you had this same problem (AC idle up) on your car (and I'm guessing you did a conversion too), was it due to the conversion to gen 3 3sgte and not the AC amplifier?
Just making sure it's not worth my while having a look at the AC amplifier.

i believe the reason it happens is because the a/c amp in the early models puts out a different signal than the a/c amp in the later cars. 
its the a/c amp that tells the ecu that he a/c is on via a/c pin on the ecu harness. 
 
if you build the cheap relay above you will be sorted. this idle issue is not due to a fault, just a difference in electronics.

Have the same idle issue after the gen3 swap, have not gotten around to sort it. I understand it's the signal in the gen3 that the ecu receives is reversed. Is it worth applying a similar fix above to the trigger wire to the ecu instead of the valve itself? I guess the final outcome will be the same.

Cheers

Yep you can do the fix at the ecu harness instead. That's where I did it on mine.

You just need to decide where you are going to chop into the wiring.

Sweet. Well then good to know the AC guys didn't stuff things up. Hopefully I've got some time tomorrow to give this a go. Chopping into the wiring is going to be the hard part haha

If you haven't started the wiring yet I would probably tackle it as follows.

• Cut the neg/ground wire about 4-5cms back from the a/c plug and extend both sides of it to the relay.
  • Connect the wire which goes to the back to the plug to terminal 30 on the relay.
  • Connect the wire which comes from the ecu to terminal 86 which is the relay coil.
• Tap into the pos wire and run to the relay. (no need to cut through it completely)
  • Connect the wire to terminal 85 which the other side of the relay coil.
• Make a short length of black cable up with a ring terminal on the end and connect this from a bolt on the body somewhere to terminal 87a on the relay.
• Final step is to plug the a/c plug back into the a/c valve and see what happens.

I think a 5 pin relay, some wiring and assorted crimp plugs shouldn't cost much more than about $25-30 if you have none of it already.
 

Done!!! It works now like it should, idle increases when AC is turned on, then decreases when AC is off.

Nick, I did it pretty how you explained it above... I had a look at doing it in the boot near the ecu but was too much of a stuff around to find the right wires.
I'll post up pictures tonight :)
Now I just need to get a nipple welded on the BOV joiner.

Congrats! Glad it fixed your problem :)

Ok, so with all the effort Mrskylighter went to helping me fix this problem, it's only right I put up pictures on this problem was fixed. 
Problem: After conversion from a NA to a 1995 Gen 3 3sgte, the AC idle up did not work properly due to a difference in electronics between the NA and Gen 3.

• With the AC on, the idle dropped and the engine struggled (when the idle should actually increase).
• With the AC off, the idle increased and the engine revved slightly higher than it should.

Hence, the AC idle up was not working as it should.
(The following is credited to Mrskylighter and will only work if the negative is being switched, not the positive.  Also, for some strange reason the red wire on the AC plug was actually negative, and the black and yellow was positive).
 
This is the AC idle up (VSV) plug.

 
I cut the negative lead (in my case it was the red wire) and soldiered on about 200mm of wire to each side.  I kept the colours of the wires the same to avoid confusion.


 
Put some heat shrink on to cover up my dodgy soldiering haha.

Crimped the other ends of the red wires with some male connectors.

 
Stripped back some of the black and yellow wire (didn't cut) and soldiered on a piece of wire.  (Note: this was my positive lead.)  Couldn't heat shrink this one so I put some tape on.

 
Put a crimp on the end of that one and hooked them up to the 5 pin relay.



Red wire, ecu end - terminal 86
Red wire, plug end - terminal 30
Black and yellow wire - terminal 85
Earth lead to body - terminal 87a
 
I also put an earth lead on...you can see it bolted to the body on the right in the picture above.
 
Finally, made it look legit haha.

 
All works fine after plugging the AC idle up plug back in :)
 
 
 
 

Apologies, I have given you a bum steer, the gen 3 in our car does have the nipple below the BOV. I have been playing with modifying a hot pipe but it is a gen 2, I must be getting old ....

I have all the bits to do the AC mod, just haven't had the time to do it.

Cheers