Cold & Warm Base idle relearn routine:

Let the engine completely cool down, turn off All electrical loads & wipe the computers memory by disconnecting the B- cable for at least 15 min, if it's hasn't already been done, or open a door, turn a light switch on, or push the cigar lighter in, to provide some resistive load to discharge the KAM memory faster.

Then turn off All electrical loads so you won't make a spark or cause an electrical surge & reconnect the B- battery cable.
Start the engine cold, let it idle down some, then slowly shift into each gear, including Reverse, long enough to feel each gear engage, ending in "N" or "P" & without touching, moving or turning anything on, let the engine fully warm up, then slowly shift into All gears again.

This will enable the computer to properly relearn its cold & warm idle strategy after a KAM memory wipe.

Ford also has a rather extensive "drive cycle" routine here Ford Motor OBD-II Driving Cycle | Car OBD Diagnostics, ECU Chip Tuning & Auto Repair Support but I've never had any driveablity problems if I perform the cold & warm idle relearn, so never have done it, or needed to use it if first doing the idle relearn routene.

One might have to do it if your trying to reset all the IM monitors, to pass an emissions test shortly after a memory wipe, or are having adverse driveability problems.

What we need to know or establish in this case is if the computer has learned the proper base no load idle strategy. If it's relearned it with the AC on, it might want to over rev the engine when the AC is turned on.

If the base idle is ok, then I was looking to try & isolate a vacuum leak in the heater/ac control panel or actuator, by having him disconnect & plug it's engine vacuum source.

If that solves the idle over rev when the AC compressor turns on, then the problem is likely somewhere in the cabin around the heater/ac control panel, or it's vacuum line connection to the blend door, or maybe it's vacuum actuator.

So that's kinda the method to my madness!!!! lol