I don't think there are actuators inside of the housing. I just took mine apart and everything was mounted on the outside of the housing. There are doors on the inside, and yeah, if they are broken, you will need to fix them, but there is a good chance it is the actuators on the outside. Also, I don't think you will need to evacuate your AC system for this repair or remove the entire dash. This only needs to be done when removing the housing, which you shouldn't need to do unless the doors themselves are broken.
Apparently, per the FSM, a dealer scanner should be able to help. "The mode door actuator can be diagnosed using a DRBIIIt scan tool. Refer to the appropriate diagnostic information."