68 LS2 Camaro

I have an LS2 out of a GTO (2005 I believe) with an E40 computer. I have a Vintage Air Gen IV unit I am installing and do not know how to wire the Vintage Air unit to the LS2 computer so the computer knows when to turn on the fans, bump the idle and turn off the compressor at a maximum RPM and at wide open throttle when the A/C is on. I've looked and searched like crazy the past 2 weeks and still nothing!

vertex

subscribed!

aknovaman

iTrader: (7)

Wire the GTO compressor same as a factory GTO. If you need E40 GTO schematics PM your email and I can send them to you.

68 LS2 Camaro

I'm not using the gto compressor

kaptainkw

iTrader: (7)

I'm doing the EXACT same thing but am not yet to the point of wiring it up... 68 Camaro Convertible RS SS, C4 IRS, AME C5 subframe, a 2006 LS2 out of a GTO + Vintage Air Gen IV.

I believe it can be done and here's what I have found out:

• You need to use the Body Control Module (BCM) from the GTO
• Here's a link to a wiring diagram for an LS1 car (wires for the GTO LS2 are very similar!):
  https://ls1tech.com/forums/conversio...m-drawing.html
• You'll need to install the GTO A/C pressure sensor instead of the Vintage Air binary switch.
• I'm also using the factory cruise control and that requres the Powertrain Interface Module (PIM) from the GTO as well

Hope this helps!

kaptainkw

iTrader: (7)

You can't use the modern GM variable dispalcement compressors with the VA systems... they are designed for constant volume (on/off) cycling. Its been tried... but not for long!

garys 68

iTrader: (1)

I'm using VA and the VA compressor on my 02 LQ9.
For fan control, I added the VA trinary switch.
I have not hooked the computer into the VA setup, and I have not noticed any idle issues. I'm not sure if the computer can get an AC on signal without the LS pressure sensor. If it can, and I have idle issues, I might add the on signal using the VA heater control valve circuit.
As for the WOT, etc functions, I have not seen any way to control that through the computer without the LS pressure switch.

vertex

you need to use a sanden compressor!

Mike52

iTrader: (1)

Why??

vertex

if i am not mistaken its because they do not run 24/7 and cycle on and off vs the newer style compressors.

john59

iTrader: (2)

Subscribed

Also doing the same thing, 89 S10 Blazer LQ9/4l80 haven't gotten to the A/C yet will be using VA system as well

ls1nova71

iTrader: (4)

I don't think the original question was what compressor to use, but if you are using a Vintage Air setup, then use their compressor, you'll be glad you did. They work infinitley better than trying to use a factory compressor, ask me how I know... But back to the question, how to wire it up, well it depends if the PCM needs a 12v A/C request, or if it's run on a serial data line. I'm thinking it's the latter, and if that's the case you'll need the GTO A/C control head to send the signal to the PCM, and/or the BCM which was stated earlier along with the GTO pressure switches.

kaptainkw

iTrader: (7)

It is the latter. Here are a few more things you'll need to address:

A/C Request Signal comes through the BCM via the Powertrain Interface Module (PIM) and the serial data communication. The ECM, BCM and PIM must be set-up to communicate with each other. If they are from the same car, no problem, otherwise "communication" needs to be reestablished.

The GTO set-up needs a blower "on" signal (also via the BCM). The system won't enable the A/C request unless the blower is on at least low speed (you don't want the A/C compressor on without the blower fan running!). The BCM interpets 12v as "off" and 0.3v or less as "on". We'll need some way to generate this signal e.g. relay or DC current tranformer circuit.

The VA system uses a Pulse Width Moduled (PWM) signal to operate the blower... as apposed to the more traditional blower resistor set-up used in the GTO... hence the need for the prior statement.

Referring to the LS1/VA wiring diagram from the link above... looks like only the terminal numbers need to be changed to the equivalent GTO pin-outs. There doesn't appear to be a need for the A/C status C2 18 with the GTO set-up.

kaptainkw

iTrader: (7)

Here's a response "hot-off-the-presses" from VA to my question:

"... I have a GEN IV Sure-fit for a 67-68 Camaro. I’m modifying the harness to interface with the LSx computer.

My question is the following:

On page 20 of the 67-68 w/AC manual the BSC (which I assume is Blower Speed Control) it shows a 3-wire connection to JM2. It looks like the system is Pulse Width Modulated… Is there any way I can get a low speed fan signal from one of the 3-wires? The ECM needs a signal that the fan is on to at least low speed before engaging the compressor."

Here's the VA response:

"...The system runs the PWM on the blower @ 22 kHz. Our system won’t turn on the compressor w/o the fan running, so you could probably just use the same signal for both the compressor on and blower on. I’m not sure how the logic works on your LS computer as I understand there are several different versions w/ different logic. This is the first I’ve heard of the need to verify blower on."

I have the 2006 GTO Service Manual and will post the description of the operation tonight.

BBPanel

iTrader: (4)

Then why hasn't the var disp compressor on my factory vehicle not failed? What is it about the VA system that is different from the oem system other than the compressor?

CentralWARMK

BBPanel How long have you been using the Variable D compressor on your vechicle? I'm
thinking about using it ths same way, or maybe converting it to a Fixed displacement compressor.

68 LS2 Camaro

so i need to get the BCM? this is the only way to make everything work? I'm building a daily driving in south FLORIDA so this is very important to me that it works right 100% of the time

ls1nova71

iTrader: (4)

I've had the stock compressor on my Vintage Air in my car for years, and it hasn't blown up, but it definitley doesn't work as well as the Sanden compressor I have on another car with VA. Compressors have to be sized to the system they're on. It's kind of like putting a 750 double pumper on a 4 cylinder, it will work, but it won't work as efficiently as it should.

ls1nova71

iTrader: (4)

Or you could bypass the PCM all together, the PCM will compensate for the added load on engine when the A/C is on, I have three cars set up this way. It's just not as "seamless" as going through the computer, but you hardly notice it. And the fans can be controlled with a trinary switch.

kaptainkw

iTrader: (7)

In order to use the '05-'06 (maybe '04) GTO ECM with an increased idle with A/C, A/C off at WOT and first stage fan on you need the GTO's BCM, PIM and ECM.

I think I've got how to do it with the link to the LS1 Diagram in my earlier thread.

So starting with that diagram:

Connect the GTO A/C pressure sensor to the ECM: A = C1 55, B = C1 30 and C = C1 26

Connect the A/C clutch relay signal to ECM C3 51

Connect the A/C Request signal from the "added relay" in the diagram to the BCM C35 instead of the ECM as shown.

Okay here's the final deal. You need to fool the BCM into thinking the blower fan is on and in order to do that you need to provide 0.3v or less (I don't know if 0, meaning unconnected, will work) to BCM C39. This can be done by a resistor of the correct resistance or better yet a potentometer (variable resistor) such that you have less than 0.3v. The VA system already has the interlock to prevent the compressor from coming on unless the fan is running.