In our CYV we leave the unit set on 84 and once in a great while 83, but never lower or our place would feel like an ice box. There is something wrong with your unit.
Get a thermometer, when the outside temperature is above 80 and A/C has been running for a good while, place a thermometer in front of a vent for 5 minutes and write down the temp. Then place the thermometer in the return grill and write down that temp. There should be a difference of 14 to 20 degrees if your unit is working correctly.
Vent
return air vent
If it's bad, do what was posted earlier, call Chuck Farrell (352) 753-9497. He's the most honest A/C man in the business and knows his stuff. He'll give you the straight scoop. My home's unit was installed new by Munns in 2011, but I've never called them, I've heard and read too many stories about them. Have used Chuck twice, once the fan motor went out after 8 years and once a capacitor went out after 3 years. The Capacitor replacement and repair was $77 and the fan replacement and repair, which required two trips was $175.
We had a home before and we remodeled the kitchen and there was a wall removed between the kitchen and dining room. They took out the plywood flooring in the dining room and they saw the main trunk of the A/C unit in the sub-floor had a 2" gap, so for all those years cold or heated air was flowing into the sub-floor being wasted. If not for the remodel we would of never known. See if there is maybe an opening in the duct work in your attic, sounds like it might be wasting A/C.