Well, 1st off, mine was an OBD II & you guys, fortunately are dealing w/OBD I.
My Opinion:
You need to get the GM FACTORY MANUALS!! It has all of the wiring diagrams.
The A/C..As I recall, youall are on the right track-LOOK AT THE "a/c Request" wire.
The 95-99(2000 for some) A/C wiring is the same. The control head is a computer.
I'm not sure how you can get the 95 dash to work with the 01(DMAX) since all of the inputs(outputs?) are different & changed again several times.
I used the 01(actually 01-03 I think)DMAX dash & it is usable/fitable(if that's a word)
I need to read the posts again.......