Generically, freon air conditioners should provide a 20-30 degree F. cooling when working properly. With the unit running measure at the air intake, record the measurement; measure at the AC vent nearest the AC unit itself; subtract the 2nd measurement from the first.
In high humidity areas, make sure the AC unit on the roof is discharging the condensate water to the roof - drill additional drain holes in the lower corners of the AC roof unit base, if needed.
I have a foil and bubble wrap insulation product, Reflectix, over all of my windows since a very hot central California summer when I arrived here (Porterville) 2 years ago. I bought a 100 foot by 4 foot wide roll from Home Depot ($150) to lay on the roof in 2 strips this summer, but so far it has been too rainy and cold here (59 degree high today, tornado warnings) to put it up. I want to get a stronger desktop fan for my kitchen island, too. Also, I am planning on moving soon to San Diego to help an adult daughter with a congenital heart condition, and now her heart is failing. All of this Reflectix insulation will roll up and ride on the bed or in the storage compartment.