Ron Francis/RJM harness and VA

[stretch]

RJM /RF FI harness has #25 blue wire in the driver side loom next to the oil pressure wiring. My understanding is this is power for the air compressor.

The new VA wiring has a blue wire that is connected to the binary safety switch then to the compressor. once again, this is power for the compressor.

I may be mistaken, but doesn’t the computer increase the rpm once the compressor kicks on? if so, I can’t see how this happens without power coming from the FI harness. Should both of these power wires be splice together?

Obviously I’m not an electrician, so any help here would appreciated.

 

[DirtDonk]

This is a great question. I've been using the RJM harnesses since the very first few batches came from Ryan and the A/C circuit was an option. Meant primarily for those wanting to use an A/C compressor as an air power source for inflating tires and such. Not many expected to run A/C at the time and an air compressor would have been on it's own switch.
I had forgotten where the hookup was at the other end of the Blue wire so had to go back and consult the instructions on our site.
It's over by the relay group.

It is a separate and independent wire that is simply included under the harness wrapping but meant for the end-user to integrate into the A/C system. I don't think any part of the function is controlled through the computer in this case. Yes in it's original form the computer kicks up the idle when the A/C is turned on, but I don't see how it could in this case.
I believe you will be choosing one or the other harness then, to use as your compressor activation source. You do not need both, but depending on where your switch is you might find one or the other easier to utilize. Or even using bits of both in series to create one simple circuit.

As mentioned, the VA (assume this means Vintage Air?) wire and RF wire do basically the same thing. I also assume for now that your binary switch is the same as the low-pressure safety cutoff switch?
If so you need to bring your 12v wire from the dash switch out to one side of the low-pressure switch. Then from the other terminal on the pressure switch, you choose to either continue to run the VA wire, or substitute the RF wire. Seems to me the RF wire might be the best since it's already part of the engine harness. But how convenient it is to use still comes up as depending on where your low-pressure switch is in the engine compartment and where you mount the bank of relays.

Make sense? It's late again and I'm not sure I'm thinking clearly as I type!

Paul

 

[DirtDonk]

Now that I think about it, it would be nice to take the time to inquire of Ron Francis if inside the harness there is an A/C signal that goes up into the computer. Like I said, I don't think so, but it would not be the first time I was wrong about something like this.
Be nice to know if it's just an independent wire, or if it is somehow integrated into the EEC connector.

Paul

 

[stretch]

Alright, did a little reading at 2am. Looks like this is only a power source for the AC from pin 10. i would need another connection at pin 54. Once the computer sees a draw from the compressor , pin 54 adjusts the rpm at idle to compensate for the added resistance.

Everything that I read, says that I can just bypass all of this and just use the VA wiring. This is what I’m planning to do at this point unless the experts here disagree.

 

[DirtDonk]

Certainly the easiest way it sounds like. I almost mentioned having to add wires to the main connector last night in my comment. But Frankly the thought of doing that would almost put me off Wiring! It’s not impossible and people do it, but I hate messing with the EEC connector.