System components
To do the conversion correctly, the system must be recovered (many shops will do this free since they get to keep the refrigerant, so DON'T VENT IT), disassembled, flushed (to remove the old R-12-compatible mineral oil), blown out (to remove the flush), and reassembled with new O-rings, accumulator, & orifice tube.
For the underdash vacuum system, see this:
A QUICKER & usually cheaper way to do this conversion is to find a '94-96 factory R134a system still sealed on a junk truck with the same engine as yours, and lift it out as a unit, including the underhood HVAC box, and the hood latch support bracket; and swap everything without opening either refrigerant system.
