Does the rear air temperature change from cool to warm when the temperature dial is adjusted?
Does water (condensate) drip from the rear with the a/c on? I'm not sure where the drain is on the 92-99, but on the next generation it is a rubber flap going through the floor roughly above the exhaust pipe. If you find it, pinch it or run a pipe cleaner up and see if water comes out.
If condensate is coming out, then you'll know that the rear evaporator coil is seeing flow and it may be an issue with the temperature blend door.
Otherwise, you may have a clog or pinch in the lines going to the back. Mmaybe take a look and see if any are obviously damaged. I doubt you have a leak in them, though. A shop may be able to flush them, I'm not sure.
Sent from my iPhone using Tapatalk