The stock ecm grounds that wire when it decides it is okay to have the ac compressor run (as explained in the link I gave). The FAST doesn't do anything with that pin, so you have to ground that wire yourself to make the ac compressor come on whenever the heater controls are in max, bilevel, normal, or def. My bet is that in this case, the dfi gen VI is just like the FAST, and most likely the gen VII is as well, and you have to ground that wire yourself, since I don't think any of these aftermarket ecms control the ac compressor. But hey, I don't have one so I can't actually say "I've done that and it worked" for a gen VI.
