Times are weird now, COVID has changed everything, and you need to start thinking about things differently. Over the last 25 years our society has become more as well as more based around immediate gratification and disposable products. Take phones, for example, as something that everyone knows won’t last more than a year or two, and yet they accept it. We no longer think long term, we just want what we want, and we want it NOW! My mom still has the outdated land line PC in her house from when I was a teenager. That thing is 15 years outdated and still works nice as ever! heating and A/C systems are usually designed to work for a long period of time, and some of the high efficiency models can last over 15 years. The thing is, for your oil furnace and air conditioner to last that long, and work well, you need to take good care of them. We aren’t used to doing this sort of thing anymore, we just throw things away as well as buy a new one, however an air conditioner is special! You need to change the air filters, and check the ducts and air vents to make sure you aren’t getting accumulations of debris or blockages. I advocate a HEPA air filter, although they cost a lot more they last for almost a full year in most cases (unless you have a lot of critters). Think long term, use your system sensibly, and once in a while it helps to turn the A/C off truly and open up the house for a little natural ventilation.