[andretti]

The temperature blend doors (left and right) are controlled by the instrument panels control module. These stepper motors also have potentiometers to report back there current position. Probably in stock at your local GM dealer since they are know to fail.

You could first try to recalibrate the system as it can be done without a scan tool. Removing the IPCM fuse for a minimum of 60 seconds resets the HVAC system.

The fuse block you want is the one inside the car. Not 100% on which fuse so to be safe remove both the "I/P-IGN" 10amp and the "HVAC CTRL" 20amp.

If it's still a problem, replace the motor. Get the new part first and you'll see how it installs, a small cream colored box on the left side (gas pedal area) of the heater case under dash.

By the way, your fan issue is the blower resistor, also mounted on the heater box but on the right side bottom.