There are three components involved here, the temperature control head, the blower motor and the blower motor regulator. Usually this problem is either the blower motor or the regulator, the control units only have problems when liquids are spilled into them. To test the motor and regulator you will have to measure the amount of current the motor is drawing when the fan is turned on. You will need some electrical experience and access to test equipment, an inductive amp clamp or inline ammeter. If you don't then have to try testing it out by hitting it. Remove the panels below the blower motor, start the vehicle then turn the AC on and watch the blower motor fan, if it is turning slowly give the case a rap with your hand and see if speeds up. The motor is probably bad if it does speed up. While watching the fan, see if the shaft for the fan is wobbling, this is sign the blower motor bushings are bad and the motor needs to replaced. To test the regulator you would have to remove the fan and by pass the regulator and observe the motor. My best guess is that the motor is bad, because you live in Las Vegas, so I would expect there is rarely a time you would drive the vehicle without having the fan on. The vehicle has lots of glass,so I expect the fan to be on at the higher speed ranges too. Finally it is about eight years old, one might actually expect this to happen at this age.