Heater not working?

I have no heat and no blowing from the vents at all in my truck. Changed the blower motor, still nothing. Checked all the fuses and stuff, still nothing. Got a brand new control module still nothing. Got a new blower motor resistor still nothing, thought maybe the new resistor was faulty exchanged it for another, still nothing. There is power at the plug that plugs into the resistor, but it doesn't seem to be traveling through the resistor to the blower motor. Like when I would test the resister plug there is no power, but the plug that plugs into the resistor has 11.8 volts power. Anyone have some idea of what could be happening?

Thank you. I will check that out and see if it works.

Heater works fine while driving quits blowing hot air when I stop. Truck has 5.3 vortec motor two wheel drive half ton. Ac works well just heater problem.

Thanks for any help you might be able to give me I checked the vaccume hoses seem to be connected

Yes coolant is full ac works good and I dont know where blend air door is if something wasnt right with the door would it work ok when driving?