No, of course A/C units are designed to blow cold air, not hot air when set on COOL. You should be able to cool your RV during the day, in the sun, and not have to wait until evening. Are you sure that you don't have a heat pump unit that is capable of heating as well as cooling? You could also have an a/c unit with heat strips that is also designed to heat. Do you have a thermostat that controls the unit or do you use the knob/switches that are on the unit it's self.
Bottom line is that you either have the a/c controls set incorrectly or you have a defective a/c. The a/c unit is a closed loop system so you cannot add "freon". If it's low on "freon", the unit will need to be replaced! I'd verify my a/c setting before I did anything else!!
Days camping (2015)----88 days
Days camping (2016) ---110 days
2016 Wildcat MAXX 28RKX (33' TT), 2007 13' Scamp
2015 Ram Laramie Hemi
30 years RV'ing
12 different RV's