swandude805

iTrader: (4)

Hi guys,

I came across a great deal on a brand new BP Auto conversion harness on craigslist. It is new and untouched, was set up for a 70 Elco. The A/C was deleted. I would like to buy this and use it for my 69 Chevelle swap. But...I want to run A/C. I do have the complete stock 98 harness still that came with the engine.

Does anyone know how hard it would be, how much work it would take, and what steps I would need to do in order to ADD A/C into the BP harness? Can I use the A/C wiring from the stock harness? Anyone done this before or is there a specific A/C wiring write up somewhere?

1964SS

iTrader: (1)

What A/C system are you using? You do not need to wire the A/C into your engine harness in order to have A/C. Many people do it by simply tying into the A/C request pin at the pcm to up the idle and turn fans on, but the A/C can be stand alone as well.

swandude805

iTrader: (4)

thanks for the response...

Ok, so I dont know much about what wires are required etc but the plan is to run Vintage Air A/C complete system. right now the engine has the stock A/C compressor on it.

So with this in mind, i can run the A/C set without tying it into the harness? will i need anything from the stockk 98 harness then? if so, what should i take from it?

I am trading the stock harness and some cash for the swap harness. so he is going to let me keep the A/C stuff but i am trying to figure out what wires to keep. I know which plug goes to the A/C compressor so do i just start at the plug and follow ALL the wires back to the pin and remove it all to keep? or is there more to it?

swandude805

iTrader: (4)

does anyone else know more?

ls1nova71

iTrader: (4)

In all honesty, it really isn't necessary to tie the A/C into the engine harness. The IAC will compensate for the extra load and it will almost be unnoticeable. Just put in a trinary switch that you can get from Vintage Air to run the relay for the fans and be done with it.

busta9876

iTrader: (3)

a lot of things to consider if wanting to use the computer to control the a/c system.

f-body operating system uses 3 wire pressure sensor. Pcm commands fans on and off based on a/c system pressure.

99-02 truck operating systems use pressure switch and cycling switch. You can get 1st fan stage on with a/c based on a temperature.

03+ truck uses a serial data a/c request to the PCM, so your option is very limited on even telling the PCM a/c is to be turned on. Some VAN applications used a a/c request on a pin at the PCM.

So really, your best bet is just let the PCM adjust load on the engine when it see's it. Properly tuned the engine will handle the change in load of the a/c on/off even with big camshafts.

rigid

iTrader: (5)

Here is what I did on my 240sx with an fbody compressor and ecm. Ignore the dash wiring, the rest should apply to most any swap.

garys 68

iTrader: (1)

I'm running a 6.0 with Vintage Air and a 5.3 with classic Auto Air, both use the sanden. It's not hooked to the ecu in any way, no issues.
I did use a trinary switch to activate the fans in addition to the ecu fan temp control.

TipsyMcStagger

iTrader: (1)

I'll have a similar issue since my GTO LS2/E40 PCM is incapable of handling the A/C request signal without the original Body Control Module and Powertrain Interface Module.

For those suggesting to run the A/C stand alone and "be done with it," what about RPM overspeed protection? Isn't an RPM window switch required to protect the compressor from failure when exceeding 4800(ish) RPM?

I've not yet come across anyone who has devised a WOT compressor disconnect, but that might be moot if a window switch is used for overspeed protection?

Just seems to me there's a little more to be concerned with than the idle bump and fan control.

Tipsy

garys 68

iTrader: (1)

Vintage Air offers a WOT switch disconnect.
But at high rpm the compressor doesn't run very long before the pressure causes the clutch do disengage. So I didn't bother to add it.
http://www.vintageair.com/Instructio...%20DIAGRAM.pdf

ls1nova71

iTrader: (4)

I don't usually run my a/c when I'm racing someone, and if the occasion shows up, I just turnthe a/c off. For years cars had a/c compressors that were not controlled by any kind of computer.

aknovaman

iTrader: (7)

Gm pcm shut off the compressor above tps and Rpm criteria in the file. That's on every vehicle.

TipsyMcStagger

iTrader: (1)

I'm not familar with the VA systems. My LS2 will be going into an E36 BMW. Does the VA system use a GM compressor? Or do they supply their own?

I agree, if the intent is to run hard, it makes sense to switch "off" the AC, but 4800 (I've read that the compressor can grenade much above this speed) doesn't seem like a very high number. I'd think it would be fairly common to exceed 4800 when simply merging into traffic, no?

At any rate, it sounds like I might be over thinking much of this. Glad to hear there have been few issues when running "stand alone," as this seems to be my only realistic option. I plan to install the GM pressure switch so the PCM will know when the system is operating. Even without the request signal, the PCM (reportedly) will still operate the fans if the pressure switch is utilized.

Tipsy

TipsyMcStagger

iTrader: (1)

Yes, but if the PCM isn't controlling (or is incapable of controlling) the request signal, then the PCM can't shut-off the compressor, as will be the case when (1) running the AC "stand alone" or (2) when using a PCM (like the E40) which utilizes a serial signal for AC request.

Unless I'm misunderstanding something obvious?

Tipsy

garys 68

iTrader: (1)

Tipsy,
VA supplies their stuff with the fixed displacement Sanden. I'm not sure if there's an rpm limit, they don't mention it.
But I gotta admit, I don't think my motors have been over 4800 more than a couple times in their life.

aknovaman

iTrader: (7)

If You change the AC type to the correct setting in the file, it will be capable of controlling the compressor and accepting the AC request input not via the serial databus. Even the e 40 ecu.

TipsyMcStagger

iTrader: (1)

Any additional info you can provide about this would be greatly appreciated. I've scoured the internet and have not found a single statement anywhere indicating the E40 is capable of accepting an AC request signal without the BCM (which generates the request signal) and the PIM (which translates it for the PCM).

I also stopped in to speak with Jared at Current Performance Wiring, and was told there is no solution available for an E40 to handle AC request.

Tipsy

BP Automotive

iTrader: (3)

All gen IV ECMs cannot accept a hardwire A/C request. Just like the 03-04 DBW it is all data and CAN Bus.

Swandude,

Feel free to give me a call and I will gladly help you out with the A/C.

Bill
270-805-1777

69 Ghost

The earlier PCM's can and will accept an A/C request even if the original a/c was wired through a BCM. I am running an 04 GTO OS and PCM with it wired to accept a A/C request like an 02 411 and it works fine. This in on a factory Camaro compressor with a pressure switch tied to a vintage air system that will soon be replaced by a factory A/C box. If you are running an earlier PCM you need to use the a/c request pin even if it is not shown in the diagram. It will be the same one as a Camaro A/C request. You also need to make sure the PCM has the proper drivers. I believe the 242 PCM's don't work but the 243's do. The variable compressors use a pressure sensor a switch like the fixed compressors.

TipsyMcStagger

iTrader: (1)

Yes, but an '04 GTO is an LS1.

2005-2006 GTO's are LS2 with a different (E40) PCM.

Tipsy