As part of my job I install air conditioning units (or heat pumps as we call them in NZ) and going into summer here we have gotten really busy. We always let our customers know how to best use them and how to keep their power bills down - I thought I would share this with you.
1) Use appropriate temperature - The most efficient temperature to run most units at is between 21 - 23 Degrees Celsius ( ~69 - 74 Degrees Fahrenheit). This is obviously specific on the individual user but your unit should be set to comfortable temperature for you. If you set it too hot it will run hard and then you will switch it off when it gets to hot then back on once its cooled down, stopping and starting any device with a motor draws a lot of current.
2) Keep your units fan setting to auto - Doing this enables your unit to get the room to temperature (initially at high fan speed) and then only work to keep it at this temperature, it will switch off (or go into sleep mode) then slowly come back on to only keep room to temperature. This will stop the unit from using high and low fan speeds or continuing to run when the room is already at temperature.
3) Service your unit - Before you think you need someone to do it is total DIY. Open up the cover on your inside unit (should just pop up) then remove your filters and brush all the dust off them (outside..).
Next spray a generous amount of AC coil cleaner (or simple green) into the coils (straight metal fins under the filters) once you've done this put the filters back in and close the cover and run the unit so the coil cleaner filters through the unit.
With the out door unit you can either vacuum it out or give it a spray with the hose (the outdoor units are rather resilient)
This should be done every change of season.
Any questions or clarification let me know :)