I am working on a split system that is 1.5 ton at an apartment complex and the resident says that the unit sometimes cool nicely but other times not. I checked the charge and it was fine the compressor was running, capacitor is good and a new hard start kit was put on. The temp out of the plenum was bouncing from 76-72 but could never get it cooler. Outside fan was running fine and inside coils were pulled and cleaned about a month ago. I am in Corpus Christi , tx so the out side temp was about 97 and heat index around 107. Any suggestions on what is wrong???