L67 swap A/C

[Black92GS]

1 hour ago, Quaraxkad said:

I would use an older PCM from a different 3800, which is what every swap guide I read suggested in the first place. I used the engine-matching PCM because it ended up being easier, but there must be reasons previous swappers used late 90's PCMs instead. I also have an 2000 GTP and 98 Lumina LTZ PCM. Both of them tested to start and run the engine, but both had different transmissions and the LTZ is N/A. Both would need programming, but one of them might have a compatible switched ground AC request signal. Surely I'm not the first person to have AC in their L67 swap!?

I doubt that any of those PCMs would do what you’re wanting them too. I don’t know about the Lumina, but even 97 2nd gen cars would have used class 2 data from the BCM to receive the AC request signal. The Lumina PCM being from an NA car would also pose a different set of challenges altogether though. 
 

GM was famous for changing things like the crank/cam correlation, crank sensor patterns, sensor types etc….on the same engine over the years, so an older PCM for a series 2 L67 may not even work with a newer one. Also take into account when those write ups were written. In the mid-latter 2000s, using a 2004 as a donor car wouldn’t have been common as they were still too new, which might be why the references are to older ones. 
 

Assuming this isn’t a daily driver, I’d almost consider going the manual compressor switch route. The power steering and WOT compressor cutouts aren’t overly critical, and the low and high pressure refrigerant switches should be easy enough to integrate into a manual AC compressor switch.