Started having issues where ac would run on 1 and 2, but not 3 or 4. Could get it to go to 4 if I tapped on the knob with a lighter. Now it won't turn on at all and when I tap on the knob the radio goes to CD and back to radio so I think something behind the ac/radio console is the problem. Replaced the blower motor resistor, based on mechanic suggestion and that was not the problem. Any other suggestions? Was looking at replacing the blower motor speed control knob module, does that sound right?