My truck is a 2004 s10 with manual hvac.. The temp pot is simply a manual pot.. It is not pwm controlled and there are no other soft stop switches for end of travel.. My plan was to simply get the circuit I need to intercept the signal and while I'm wiring it, I can simply measure the min and max voltage signal and either pwm control it to match the limits, or use some resistors to adjust the min/max of my circuit so I do not overdrive the servo.. Gm themselves are not too particular on the voltages so honestly I do not think I could overdrive the servo anyways as long as I stay in their specifications.. The temp servo has 3 wires, power,ground and signal. There is no feedback signal coming out, the control and amplifier are internal to the actuator.. All I want to do is interrupt the signal going to the actuator and put in my own... For the blower I was simply going to trip the high blower relay by putting 12 volts on circuit 52 using a transistor that can provide the 80 ma it needs.. I have already got a temp sensor working so I can go full cold or full hot, or nothing depending on temp inside the vehicle when it's started..
By the way, If anyone needs a particular schematic for any gm vehicle, let me know I can search powertrain from 96 and newer and 98 and up everything...