The first and most simple step to take to extend your ac units life is to change the filter. You should change it whenever it gets dirty. Depending upon the usage, that might range from every 3 to six months. There are some filters out there which can last up to a year. Ask somebody in the hardware store for more ideas Go to the web site .
Once a year, make certain that you inspect the evaporator coil located inside the air handler to make certain there is no dust build up. When the weather begins to cool, you should inspect the outside of the air conditioning unit. You should check around the unit and make certain there is no debris on the surface area of the condenser, as that will stop air flow. Also, you should check in between the fins of the condenser to see that its not clogged with dead bugs or pollen. Spraying the condenser with a hose will normally suffice to get rid of all the debris.
Although many air conditioners today utilize direct drive motors, it is a good idea to inspect the belt in the air handler. You might have to replace it. If no change is required, you might only have to oil the motor bearings once a year.
It is also good to inspect the contactors and other electrical parts; many of them are located inside the condensing unit. The contactor runs the compressor, and the contacts get pitted and have to be changed occasionally. Various manufacturers utilize different types of contactors, so review the handbook to discover what kind you need.