Dad’s jag. Original owner with 18000 miles. Ac only blows out the defroster vent. Live in Florida so definitely need the A/C. Any suggestions? He’s also looking at front and rear brakes. Not gonna be cheap. But the blend door is the current problem.

 

Might be the vacuum manifold.
Or just a loose o broken vac line.

 

Due to lack of use and your Florida heat, the blend flap might have 'glued' itself shut. As the foam deteriorates from the heat it becomes sticky and can create greater resistance that the vacuum can't overcome.