BagD72Chevy

UPDATE- SOLUTION POSTED IN POST #9!!!!



2007 silverado classic drivetrain swapped into a 67 C10. Runs great, no problems, I added Vintage Air.

Reflashed PCM with Express Van OS 12587603 and van tune with Efans enabled and DBW. Again it runs fine.

I ran the vintage-air ac clutch wire through the binary switch and to the A/C Request on the PCM, pin C2-17. Did not put the high pressure switch inline.

I grounded Pin C2-55 to bypass the Low Pressure Switch input.

Clutch Relay Control on C2-43.

I'm not getting the AC clutch to activate. In the DVT menu I can enable and Turn On the AC clutch and it engages. So the problem must be on the request logic side. Is there a way to monitor the A/C request status through EfiLive? Or the Low Pressure Switch Status? The only PID I see is A/C Pressure Sensor Voltage which is inactive since the van doesn't use a pressure sensor.

Thanks

Illegal Vette

I had a similar problem when I installed a 2002 LS1 from a trans-am into my '82 Corvette. I initially wired it like you have yours wired without success. The only way I could get the PCM to engage the Sanden 508 compressor(presumably the one you have) was to wire in the pressure sensor instead of the high pressure switch. I'm still using the low pressure switch.

BagD72Chevy

The Express vans dont use a pressure switch which was the entire reason of changing the operating system. I'm driving over my dads tonight to borrow his Tech2 and see whats up.

On another note I ohm'd out the low pressure switch because I thought it may have a heavy resistance to cause a voltage drop but it does not. I put pressure to it with my compressor and at ~50psi it closes and has 0.6-0.7ohms resistance so the pcm would see dead ground.

BagD72Chevy

So I may be onto something, but it brings more questions.

Using the tech2 I can see that the AC Request isnt working. SO I'll look into that next. But I also noticed the Tech2 is attempting to show data for a pressure sensor and the Express Van doesnt come equipped with one.

Can anyone confirm my wiring diagram above? I know C2-43 is correct for the compressor because I can turn it on from EfiLive. Are C2-55 and C2-17 correct?

G-Body

iTrader: (4)

I`m curious to what the A/C type it set to in efilive. I can`t seem to get the demo version to let me in, but IIRC HPTuners had a very similar option. I think it should be set to analog cycling for the express van, but it might be worth double checking.

cajundragger

iTrader: (2)

I don't think these variables are defined in efilive.

But maybe they are in a CAX somewhere?

If they were defined in EFILive then the OS swap wouldn't have been needed.

BagD72Chevy

I think you are on to something now. I found a few other threads on efilive and hptuners forum mentioning this.

I need to change to analog cycling and wire my pressure sensor back in to control the fans. I can still bypass the low pressure switch presumably. Now to figuring out how to get my tune straight.

BagD72Chevy

After trying a few tunes last night I'm thinking the hardware I have is not compatible with what I was trying to do. I picked up a 2004 4.3 silverado computer this morning 12586243, same as vans, hoping it will help with the analog ac type. I have the computer wired as a van and a truck right now so I can play with both operating systems. And it is ready ac pressure.

Good Read:

https://forum.efilive.com/showthread...ma-A-C-request

BagD72Chevy

Thought I would follow up since no-one ever does:

So I did the HotRod PowerTour and the A/C worked like a charm. The manual a/c request on the 03-07 trucks in hardware level. I took apart the v8 truck pcm and the 4.3 pcm and figured out which components are missing. Swap in a van computer or 4.3 pickup computer with truck wiring. Ground C2-55 and use C2-17 for your request. Put the truck tune on it and it just works. It still reads the A/C pressure and uses it to control the electric fans.

If you use the van tune the a/c will work but it will not control the electric fans properly with the a/c cycling. The logic for this is in the truck OS & Tune.

WS6HUMMER

iTrader: (19)

Working on and LS swapped car, trying to get the IAC & idle to respond to the request signal but its not. Its an 01 suburban OS, I have voltage to C2 pin 17 but nothing happens when voltage is applied. Does the ECU need a ground signal on the low pressure pin to recognize the request signal (C2-55 like you mentioned in your post)?

BagD72Chevy

Im not as familiar with the 99-02 pcm's but yes you will need that pin grounded for the function to complete afik.

WS6HUMMER

iTrader: (19)

Thanks!