GM-GMC: heater/blower quit working, blower motor resistor, sierra 4x4

Question
I have a 2006 sierra 4x4 1500 zr1. Travelling today in -27c weather and the heater up and quit working on the highway. The speed from veichle kept heat coming thru the vents, but the blower doesn't work on any speed setting. Checked fuses inside and under hood. Changed out blower 40amp one, and still nothing. What now or did it just freeze up?

Answer
You will need to remove the shroud on the passenger side below the dash to access the blower motor.  Remove the plug and test it for power with the switch in all the positions.  If you have power and ground at the plug, but no fan.  Remove the fan and inspect it.  If it's not frozen, you will need a new one.  If you have no power at the fan and the fuses are good.  You likely need a blower motor resistor.  Check the fan first.
Hope this helps