AC Request

[NC_John]

Originally Posted by First c10

Hey john. I looked into this also
I am running an e38 ECM. I will have to use the stock pressure switch and wires from pins 12/13/43 (I think). For me this will control cooling the Fans and idle control. Or at least I hope.
The request wire (59 I think)just turns on a relay that went to the compressor. I am going to use the old air product (my ac) binary switch to control the compressor.
But if anyone knows of a single wire that works I want to know as well.

I suspect we have different goals with our projects. I am currently (and successfully) running my vintage air completely independent of the pcm. My fans are controlled by an entropy fan controller setup (which is a pretty slick setup in itself).

My tuner just wants the pcm to know when the ac is on so he can tune around it. Maybe necessary, probably isn't, but if I can do it easily enough and it will make him happy, I'll do it.

He actually wants me to provide the pcm with ALL the factory ac inputs but there is no way I am going through that ordeal. It's completely unnecessary with the vintage air doing the thinking. He's way more versed doing work on the newer stuff and is not as familiar with what's required with a swap.

Sounds like you might be trying to do the ac control through your pcm?

[87chevy.com]

Originally Posted by NC_John

I suspect we have different goals with our projects. I am currently (and successfully) running my vintage air completely independent of the pcm. My fans are controlled by an entropy fan controller setup (which is a pretty slick setup in itself).

My tuner just wants the pcm to know when the ac is on so he can tune around it. Maybe necessary, probably isn't, but if I can do it easily enough and it will make him happy, I'll do it.

He actually wants me to provide the pcm with ALL the factory ac inputs but there is no way I am going through that ordeal. It's completely unnecessary with the vintage air doing the thinking. He's way more versed doing work on the newer stuff and is not as familiar with what's required with a swap.

Sounds like you might be trying to do the ac control through your pcm?

Lol, yes you can run a standalone ac but well, the dang pcm just wont know it's on... so your tuner probably does know his stuff. More than likely, he will just tell you, since you couldnt connect the ac system like factory, dont bother me with ac on idle problems.

[ls1nova71]

I have 2 swap cars both with over 100k on them and both have vintage air and never had any issues running the A/C as a stand alone system.

[First c10]

Originally Posted by ls1nova71

I have 2 swap cars both with over 100k on them and both have vintage air and never had any issues running the A/C as a stand alone system.

I have 2 as well , 1 with factory ac and another with old air hurricane system. They run fine but have a little stumble when coming to a stop with the ac on or cooling during idling for an extended period of time with ac on.
My current project I would like to untilize the factory pcm to control cooling fans so I don’t have to add other controllers to turn fans on. Which will also keep the idle issue.
If the pcm can get the info it can regulate idle and cooling fans.
I am trying to keep it simple as my system is matched. I do know segment swaps are a little tricky. Let us know what works.

[NC_John]

Originally Posted by 87chevy.com

Lol, yes you can run a standalone ac but well, the dang pcm just wont know it's on... so your tuner probably does know his stuff. More than likely, he will just tell you, since you couldnt connect the ac system like factory, dont bother me with ac on idle problems.

My tuner has been having fits with the driveability of my build. Parking lot (1st gear) was a nightmare with jerking and bucking. Coming down through the gears on decel to a stop was also a problem with the truck almost always stalling at the bottom of first gear. When it didn't stall the idle would instead hunt up and down for a while before it would settle down normally. He finally got it sorted out and its about 95% right now. His biggest complaint has been the limitations of the gen III pcm compared to the newer ones.

They've (builder and tuner) have got a ridiculous amount of time in the tuning already so even though I haven't experienced any idle issues with the ac, I'm happy to provide him with this input.