<human>: How do I know when it's time to replace my air conditioning unit?
<bot>: The best way to tell if you need to replace your air conditioning unit is to check the manufacturer’s warranty and make sure that it has not expired. You can also look at the age of the unit and see if it needs to be replaced based on its expected lifespan. Additionally, you may want to consult an HVAC professional who can inspect the system for any signs of wear or damage.