Know Your HVAC System Well
As a homeowner with a central HVAC system in your house, it will be on you to prevent problems, to help the system work in an efficient manner, to have issues dealt with in a timely manner, and to know when it's time for a new system to be installed. You can find some basic information on these things here:
How to prevent problems
While time and wear and tear will eventually take their toll on a system, there are still things you can do to prevent premature problems.