Based on you statement I am starting with the assumption your fan motor is turning. That rules out the fan control or the motor as an issue. There is a possibility the fan motor is turning but is spinning in the fan, rather than turning it, but let'* start with the air mix actuator door.
Follow all the instructions in this link, including the information it links you to:
If at some time during this work you are sure the actuator door is open, turn the fan on and make sure it is turning and pushing air.
Update us as you work through this.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)