Ellis Juan

iTrader: (5)

2006 GTO LS2/T56 with speartech modified engine harness. He brought the single green ac wire out under the dash and brought out the high pressure switch plug. I have a vintage air setup that runs a sanden compressor.


The high pressure switch and plug are pretty much self explanatory, but my question is how I will get the PCM to turn the AC comp on and off? The sanden only has one black wire for power. The engine harness AC comp plug has 2 wires I believe. Is the green wire basically used to trigger a relay? Not real sure how to go about hooking it up.

I know the high pressure switch will tell the PCM to cut the compressor off and on, but im not sure how to interface the engine harness compressor plug, single green wire and the vintage air controls. Any help would be great!

rsz288

The PCM wont operate the air con by itself/outside a production car. The wire needs to be direct connected to a switch.

Ellis Juan

iTrader: (5)

Well that seems simple enough. So I will just connect the green wire to my vintage air ac power control switch, which will tell the computer to send power to the AC and then the high pressure switch will tell the computer to cut the compressor on and off. correct?

What about the 2 wire compressor connector from the engine harness? How do I connect that to the 1 wire sanden compressor?

garys 68

iTrader: (1)

I'm running the VA on my 68 corvette with an LQ9. I'm not using any computer functions with the VA system. No problems at all.
I'm using a trinary switch to control electric fan function, so the only thing I'm missing w/o the computer is the elevated idle (not very noticable) and high rpm disable. And I'm guessing at 5000rpm the compressor doesn't cycle on very long even without the disable. Others have integrated the original pressure switch but I dont see any reason.

Ellis Juan

iTrader: (5)

I did the same with my hot rod air kit on my last 76 corvette build with an lm4/t56. I ran the standard binary high pressure switch and just connected a relay to the AC switch to trigger the fans. I would notice a slight bog/stall feeling when I would slow down at a light but overall it worked ok. I just wanted the system to be integrated this time around.

garys 68

iTrader: (1)

Do a seach here on AC systems. I was worried about it, but like I said, no problems.
I think the concensus is that you need to weld in the original pressure switch to get the computer to work correctly.

Ellis Juan

iTrader: (5)

Yeah i already have the gto pressure switch and the fitting to be brazed in on the on the high pressure side. I just figured since I had all the parts might as well make it kinda sorta factoryish. I have a trinary switch that came with the vintage air kit as well.

Old Geezer

iTrader: (3)

When I asked the tech @ V/A, he said there are so many variations of LS systems, that they do not get involved in supplying pcm based controls.

bczee

iTrader: (12)

Don't you need the BCM (and controls) also to control the Factor AC setup ?

KENS80V

iTrader: (16)

The LS2/LS3 systems send a turn on signal (GMLAN serial data) from the HVAC controller to the BCM. The BCM then sends a signal via the GMLAN serial data to the ECM. You would need a factory HVAC controller and a BCM to make it work. The LS1 PCMs are easier to make work as there is no BCM in the the signal path.

LS1GMCTruck

iTrader: (2)

Correct. The two wire A/C connector has a green & a black wire. The black wire is a ground. Crimp an eye terminal to the end of it, and ground it to the Sanden compressor housing. Wire the green wire to the compressors clutch activation wire. Just make sure this green clutch wire is activated via a relay & you're good to go. This is the info you needed, right?

Ellis Juan

iTrader: (5)

Yes thats what I wanted to confirm, that you just hook the black wire to ground and the green wire to the compressor. As far as the green wire under the dash, I dont believe I need the BCM or a factory hvac. Thats why Speartech brings it out. I will give them a call today and confirm that this green wire just needs a switch power source.

KENS80V

iTrader: (16)

If you are using the LS1 PCM then you don't need a BCM and HVAC controller. If you are using a LS2/LS3 ECM then you do. You haven't told us which one you're using.

Ellis Juan

iTrader: (5)

It's the gto ls2 harness and PCM. I tried calling John today at Speartech but couldn't catch him. I'm thinking I don't need the bcm.

68Problemchild

iTrader: (1)

I am doing the same with an L92 and a Current performance harness. Please let us know where you end up after talking to John.

So you are at green to compressor power and black to ground on Sanden. Sounds OK.

Chris442

iTrader: (1)

I'm running basically the same setup for A/C using the Speartech harness and an E38. I hooked the green lead up to the wire that would switch on the compressor relay in the Vintage Air harness.

The factory compressor has a 2 wire connector, as was stated above. I hooked the power wire from that to the compressor clutch wire on the Sanden, and just left the ground alone. Everything works great.

BTW, using this A/C setup along with a C6 factory PWM fan module makes for a very slick fan setup.

Ellis Juan

iTrader: (5)

I spoke with Speartech today and he said to just hook the green wire under the dash to the vintage ac power switch, no BCM needed.

Chris442, with the AC hooked up the way you have it does the computer cut the compressor on and off at rpm levels? Does the high pressure switch from the PCM cut the compressor off?

Vintage air sent a trinary switch which would kick the fans on when the head pressure was high, but obviously your pcm wouldnt know when the AC was on or off.

flyinsquirel

So just to make sure I understand this. You hook the vintage air power-to-compressor wire to the green wire from your harness(AC request to the computer I believe), and then the factory power- to-compressor wire to the compressor. So it's basically a two wire hookup for the computer to control the fans and the compressor just as in the origianl car. Is this right?

Do you need the factory or the vintage trinary switch, or does it matter? I've seen some people braze in an extra port and use both.

Chris442

iTrader: (1)

You could set it up that way, but it depends on how the computer is programmed. In the programming, you can set it for engine speed and/or WOT cutoff. Based on some math I've done, 4000 engine rpm is good limit for the Sanden if using the stock crank pulley.

The pressure sensor will cut for high and low pressures, but in day to day use its main purpose is to control the fans. With the PWM controller, I can use the programming to dictate by percentage how much the fans run based on the high side pressure. On the GTO programming, this will come set up to run 2 fans, with the 2nd coming on at a fairly high pressure.

I haven't tested all of the stuff you've mentioned directly, but I can use my laptop to turn on/off the compressor, and I know that the fans work with rising pressure. IIRC, with no charge it would shut down the system if you tried to turn it on, but it's been a while.

Another thing to note is that the torque values for the A/C compressor in the ECM probably need to be changed for this to be just right. On the Gen 4 computers, this is how it knows that it needs more air to run when the compressor is engaged.

Ellis Juan

iTrader: (5)

Thanks man. Sorry I should have specified. I am running HP Tuners and just wanted to make sure I would have control if I hooked it up your way. I have all my fan settings on 100% right now. I will tweek them further when I begin tuning.