Ac problem on 93 Camry on 1993 Toyota Camry

Hi, I have a 93 Camry. When I run the AC all the vents blow air but only one vent blows cool. What could be the problem?

Asked by for the 1993 Toyota Camry
The system could be low on refrigerant, or there could be a problem with the system that controls the temperature and air flow through the vents.