With the engine off, and key in the run position, listen for the sounds of the HVAC doors moving when you turn the know through its range of options. Can you get the temp to go from hot to cold, and back? If so, your blend door motor is working. While you are at it, check out the filter for the system accessed from under the rood on the pass side (IIRC).
You may also look behind or under the glove box to be able to watch/hear the HVAC motors work as you turn the knob.