When it's really hot or really cold it seems as though your heating and air conditioning unit is running all the time. One way to reduce its run time and reduce your energy cost is to install a programmable thermostat. This will allow you to raise or lower the temp at times when you are not at home.
Setting up a schedule will allow your system to come on at times when you need it. Its important to not have too much of a differential between scheduled temperature as it will take some time for the unit to satisfy. What I mean is, for example; in the winter if you set it for 62 during the day and set it for 70 at 6pm when you get home. Realize that it will take some time to go from 62 to 70 degrees.
Another easy tip is try adjusting your temp 1 or 2 degrees below or above your normal temp that you normally have your thermostat. Just this slight adjustment can save you every month. If you have any questions about programmable thermostats or need advice or help installing one.