Since hot air rises and cold air falls, in the summertime close some first floor supply registers, and open some upstairs; do the reverse in the winter.
When rapid temperature change for comfort is desired, don't set the thermostat higher or lower than the desired temperature. That doesn't cool or heat a home any faster—it just makes the system work longer.
Try to limit the amount of heat entering your house during the summer. Try not to use lights and appliances during the hottest part of the day—they generate more heat! Covering your windows with drapes or awnings will help keep the house cool. Every little bit will help and minimize the use of your air conditioner! That means you save money!
In winter, try to use the sun when it is out! Open drapes and shades in the cool weather to let the sunshine in during daylight hours. This will help to warm up the house. Then pull down the shades and draw the draperies at night to help retain the heat.
Also, keep draperies away from radiators, so the warm air has a chance to circulate throughout the house.
Air-conditioners are designed for a 15 to 20-degree temperature differential. Your system is working properly if it is 85 degrees in your home when it is 105 degrees outside. The air-conditioner will dehumidify your home if it has a chance to run long enough.