There are a few factors to consider. First, the average life of an air conditioning unit is 15-18 years. If your unit is more than 15 years old, you might want to consider replacing it before it breaks down. Additionally, older units may use R22 refrigerant, which is being phased out due to environmental factors, making R22 very expensive. Finally, if you are considering moving, a new air conditioner can enhance the resale value of your home.
Increasing and more expensive repairs
As units age, repairs become more frequent, and more expensive. If you are experiencing more repairs and more costly repairs, consider a new unit.
Rising utility bills
If your utility bills are increasing and you have not changed the way you are using your AC system, that could be a sign the system is not as efficient as it used to be.
Your home is humid
A well-functioning AC unit will remove humidity from the air. If you notice the air becoming more humid (you are experiencing a cold, clammy feeling), that is another sign you may need a new unit.
A well-functioning unit should also provide the same level of cooling in every room. If that is not occurring, consider a new unit.
As systems begin to wear, they may become noisier. If you are noticing more noise coming from your system, that could be another sign it is time to replace it.