It really depends on what type of actuator it is. Servos, steppers and linear actuators are commonly used. A servo would be controlled by PWM and by varying the PWM frequency to determine its position. A stepper would require a driver board and some sort of control software probably with an encoder to send back position info. A linear actuator would just use timed pulses with a limit switch at each end of the travel. If you wanted to know where the control position is, you would need some sort of encoder or at least a variable resistor.
Does the Fusion Brain output PWM? If so, then a servo would be very easy to implement. If the actuator is a stepper, then a control board would be needed and the Fusion Brain would output one digital pulse per step (or microstep). A linear actuator would only require voltage to drive the motor and reverse polarity to reverse direction. It travels as long as voltage is applied until it reaches a limit switch.
For the temp control, many vehicle use a dual stage control. The heat side moves a cable that opens and closes the valve to the heater core. The cold side is usually a control like a rheostat that controls when the ac compressor turns on and off.
I'll be converting the mechanical climate controls to automatic using servos in my Montero Sport.
How many wires does the actuator have. That might be a clue.