Parts listed below

How to test and replace a blower control module on a GMC Envoy.
This GMC Envoy was brought to me with an inoperable HVAC blower. A few brief tests revealed the Blower Control Module had failed and was not providing power to the blower motor.
Gm vehicles with digital climate control use a Blower Control Module instead of a Blower Resistor to control power to the blower motor. Failure of this module and it's manual HVAC counterpart the Blower resistor is common.

Link to video on HVAC actuators for the people who keep telling me the defrost issue is just a setting:
   • GMC Envoy HVAC actuator Replacement  

Parts used:
Blower control module
OEM AC Delco #: 1581773 https://amzn.to/2DYK4ZC
Genuine GM GM #: 19260762 https://amzn.to/2V6mno4


Applies to any vehicle with digital climate control that is built on the GMT 360 platform which includes
0209 Chevrolet Trailblazer,
0209 Gmc Envoy,
0204 Oldsmobile Bravada,
0307 Isuzu Ascender,
0407 Buick Rainier and
0509 Saab 97X
Also applies to many other GM vehicles which use the same digital climate control module.