Seeing the warnings when your central heating and air conditioning system is on its way out is a tricky thing.
If you know what to look for, you will notice them and be able to act accordingly.
Sometimes you can even extend the life of your central heating and air conditioning system unit if you can call your local heating and cooling specialist when you start to see these signs. Sometimes a general heat and a/c tune up and check up can fix the issue and make your central heating and cooling unit last some months to a year longer than it would if you did not catch it in time. This was the case with my central heating and air conditioning system. I seen the signs of it starting to go out when it took long to shut off and start up. Also when it was making loud noises while running. I called the local heating and air conditioning company right away and had them send out a certified heating and air conditioning specialist to have a look at my HVAC unit. Once they did they were able to do a few things to extend its life. My central heating and cooling system ended up lasting an extra 8 months before I had to invest in a brand new and up to date central heat and a/c unit. This gave me time to get the investment together to be able to purchase the new heating and air conditioning system. I was so glad that I seen the signs to be able to buy myself some time.