A/C ecm wiring for idle

[Justin71105]

Originally Posted by A1971Blazer

Good info, thanks!

My PCM is mounted on the back of the core support, so there's easy (relatively) access to it. I could easily add the wires and pick up the 12v signal at the compressor connector, ground would be simple as well.

Mine is a DBC (red/blue) but I suppose the PCM would be looking at the same i/o for a signal, and the IAC would make the adjustments to the idle.

I will need to look at my harness to see what wires may be there, and the PCM pinouts that correspond to the AC signal.
I'll hook up the scanner and check some readings first.
Attachment 2425299

From my reading on this the red/blue all have the needed circuitry inside the ecm.

Green/blue like mine only a certain set of them have the needed circuits inside the ecm, lt1swap has a list of them and mine matched.

They also have the step by step to add the needed chips inside blue/green ecm missing the circuitry to make it work but I was happy I did not have to go through all that.

For my compressor SD709 (04709-VMA) from VA I have AC set to Analog cycling (fixed compressor) in tune and it would need to be set to Analog for a variable compressor.