Each central air system works to cool air by 15 to 20 degrees at a time. As an example, if the indoor air temperature is at 80 degrees, the AC system takes that supply of air and subtracts 15 to 20 degrees of heat before releasing it back into the home air supply. Because it mixes with the other 80 degree air that has not been conditioned yet, the air you feel will be cooler but not necessarily the temperature that you set on your thermostat. It takes time for the indoor air to reach temperature equilibrium.
However, if you detect the mixing of conditioned air and the indoor air supply is not the reason for poorly conditioned air there may be a greater issue. Though air is still conditioned, it is less efficient, working twice as hard to cool the same amount of air.
If your air is not cooling air in 15 to 20 degree increments, a maintenance call is required to restore proper function and efficiency levels.