The correct temperature for an air conditioner depends on each person and their liking. However, I believe that a good temperate would be around 70 degrees.
Most a/c will get a temperature difference of 20-25 degrees between the return and the supply temperatures at the unit when the outside temperature is between 75 and 95 degrees.
Any AC unit proportionate to a certain size room should be able to cool that room to temperatures between 79-59 degrees. If not, the AC isn't cooling properly.
