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. Keep a clean air filter in the system at all times. Also, have it serviced professionally before you turn it on and start using it for the summertime.

How to help the system work efficiently

Again, a clean filter is important and one of the best things you can do to keep the system working efficiently. However, you also want to winterize your home so the warm air generated will stay in the house. You want to be sure to have any leaks fixed as soon as they are found. Give the condenser shade at the hottest part of the day. 

How to find issues that need to be fixed

Sometimes you can have a big problem happen suddenly and there isn't anything that you can do about that. However, there are also problems that can show themselves slowly and go on for a while before it really causes big problems that can no longer be ignored. It's going to be better if you are able to recognize those small things that are going on so you may be able to fix them and avoid those larger things from happening at all. Some ways your HVAC will warn you of things going wrong is by making sounds that can range from a hissing sound to grinding or banging sounds. It can also put out warm air when you're asking for cool air. Or, the cool air it does put out may not be as cool as it should be. 

How to know its time for an upgrade

If you have an older system you can't have connected to home automation, you may want to upgrade it. If you have an old system that is starting to demand more attention or causing higher bills, then this would be another time when you want to give in and consider having it upgraded with a new one. 

If you need AC repairs, contact a contractor in your area.