70 lemans ,the heater control is jammed can't see why I noticed the front speaker was removed thinking a nut fell in but don't see one, anyone have theirs jam and find a different cause?

Is the heater control jammed on all levers or justa one? If all are jammed, then i would suspect they are rusted together. If it is one, then I would keep looking.

You can remove the glove box door and glove box insert to gain access to the back side of the heater controls and radio. Replacement controls are easy enough to find, especially from Frank’s Pontiac Parts.

cable from the heater control is probably bound up or off the jam nut on the top of the suitcase inside the car. Like frosty asked is it the cold to hot or the different levels? ie defrost,bi level heat etc...