The knob you physically use to adjust from A/C to heat is stuck and does not turn?

My A/C adjuster nob was recently snapped off and I had to replace the entire A/C temperature control panel. So, the control panel was replaced but it is still the same problem. The knob you physically use to adjust from A/C to heat is stuck and does not turn. It's very stiff and will not turn. Now my research tells me I believe it’s the cables/wires in the back of the control panel. I need an east how to video relevant to my exact vehicle showing me what cables or wires I should be ordering and how to do it. Any suggestions?