What temperature should come out of ac vents?
There is a range of acceptable temperatures. 55 to 61 degrees would be an acceptable range for a properly working ac cooling process. Old ducts, with poor sealing and insulation, or ducts that are in an attic with poor insulation can affect the temperature drop.
Most homes can generally maintain temperatures between 70-75 degrees in the heat of the summer.
Programmable or “Smart” thermostats will do a much better job of striking the perfect balance between personal comfort and energy savings. It’s important to keep in mind that the temperature you set on the thermostat will not make the air coming out of the supply registers any colder.