Maybe I missed it but the ECM whether GM, Holley, ect needs to be told the AC is on. Most swaps we see the ECM has no communication with the AC system. If you look at Stielow's builds he adds a GM pressure switch to the Vintage Air plumbing. This allows the ECM to reference the "AC on" rpm tables. If the ECM doesn't know that the AC is on there is nothing a tuner can do for you aside from bumping the base rpm tables to a point the vehicle won't stall.
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