I just bought a 2001 suburban. Ac blows great out of middle vents. I can only get the heat to work if I turn fan speed down very low and turn dial to heat. Then shut off engine and restart,, the heat will then blow hot,,, I took off blend door actuator and looked inside, all gears look great. Another issue is I can't get the air to blow for defrost of floor board. I located the actuator for this above the accelerator pedal. Does anybody know how many volts are supposed to go this this acutuator? or a trouble shooting method,,, or any suggestions? Thanks in advance