Depending on the type of actuator and HVAC control head you have, you may run into more problems or even possibly damage the actuators. The control head may be connected to end stop sensors that tell it when to stop driving the actuator or it may be using pulse count or feedback to determine the position. You could burn up the actuators if you continue to drive them once the end stop is reached. Also, your control head may be confused if the actuators are not in the same position it thinks they are in (some actuators don't provide constant feedback). You may be better off intercepting and replacing the value the control is reading from the temp pot behind your temp knob.
For the blower control, you may have high current contacts in the control head or blower control module that receives a signal from the control head. If it is the latter I would recommend doing the same thing and sub in your own resistance value for full blower.
Out of curiosity, what is your vehicle make/model/year?