I am having a little trouble with the 1997 k1500 air, it only blows defrost no matter what setting you have, and nothing comes out any other vents. I changed the hear control panel with a known good used one out of dads truck, it did nothing. I have checked the fuses but it seems there is no power to the actuators, the one by the drivers pedal never moves. I really don't know where to start checking anymore and I don't like throwing parts at things and guessing. What should I check now?