This trucks sits about 3 months at a time and Last March the hvac blend doors quit working. So it sat some more and in the summer I started to mess with it. First I reset the hvac unit a few times by pulling the fuse and starting the truck up and not touching the unit, to no change. Then I replaced one of the actuators with a new gm one and reset the hvac unit, to no change. I even left the actuator out to see if it would move and it does not move, even when resetting the unit. I got a friends old tech 2 and pulled these codes.

B0228 B3779 B0423 B0413

Last week I bought a hvac unit out of a wrecked suburban to toss in to see if was maybe the unit but it still does not do anything even when resetting the unit. I know they have different part numbers. In both units the blower fan works. It’s been almost a year and I still have not been able to find any info on this issue. I’ve never had any issues with the truck since new. Any help would be appreciated. Truck has every option that was available if that matters. And everything works but the hvac.