why does my a/c temp rise from 43 deg's to 65 deg's at the middle dash vent

Did you have the system on max air or normal air settings. Normal air conditions the air from outside max air recirculates the air in the cabin. Start your system on normal then when it gets a little cooler then turn it to max. If you want to have it looked at give me a call to make an appointment.

A vehicle that age may have blend door gasket failure, pinch off one of the heater hoses to disable the coolant circulation, and check the duct temp, if that helps, just install a water shut off valve in one of the heater hoses.