Pressure and temperature are relevant, as pressure lowers (loss of charge), so does temperature. So, if a system gets low on refrigerant, it usually gets colder and freezes the evaporator coil first.
I would guess you have a blend door broken or stuck.
Most people try and add more refrigerant, and then the pressure increases, and the temperature rises, so it does not cool worth a darn.
Have someone, who has knowledge about the system, diagnose it first.
Jess