No cabin filter on the '93. Look on top of the black HVAC box on the passenger side at the base of the windshield. Is there an embossed pattern that says "CUT HERE TO SERVICE"? If so, cut that out. That will give you access to the evaporator which may be clogged by now. You could clean it with a brush and vacuum. You would then have to get inventive on how to patch the hole. Duct tap, aluminum tape, beer can & RTV. Be advised that those HVAC boxes tend to get brittle and crack, so do so at your own risk. That makes me think of another point. Maybe it has already started to deteriorate. If so, your blower is blowing some of the air meant for the cabin out under the hood, thereby reducing the pressure at the vents. Somewhat like a leak in a garden hose. Check that out first.