1998 aurora hvac problem

OK, During the summer periodically the AC will blow hot air with 30 sec. it will switch back to cold. Shortly after that we noticed it wasn't blowing hard when then the control panel was set on "face" not sure what else to call it. At this point i figured it was a blend door actuator but never got to fixing it. Even more recently I noticed that it was cycling through all of the blend doors like it would do if you seleted defrost, feet and face but with out me doing anything. And now it is stuck on heater no matter if the HVAC is off. I have a 95 parts and switched out the dash control but still no luck, what else could it be? HVAC control module? if so where is it?