The first and most basic step to take to prolong your air conditioners life is to replace the filter. You should replace it whenever it gets filthy. Depending on the use, that might vary from every 3 to 6 months. There are some filters out there which can last up to a year. Ask someone in the hardware store for more ideas.
Once a year, make certain that you check the evaporator coil found inside the air handler to make certain there is no dust build up. When the weather condition begins to cool, you should check the outside of the a/c unit Plano Air . 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 congested with dead insects or pollen. Spraying the condenser with a hose will normally suffice to get rid of all the particles.
Although many air conditioning units today make use of direct drive motors, it is a great idea to check the belt in the air handler. You might have to change it. If no change is needed, you might only have to oil the motor bearings once a year.
It is also good to check the contactors and various other electrical parts; many of them are found inside the condensing unit. The contactor runs the compressor, and the contacts get pitted and have to be changed occasionally. Various manufacturers use different types of contactors, so check the manual to find exactly what kind you need.