The answer to 'tune-up not working' is that there could be several common causes, such as a faulty thermostat, dirty air filters, or issues with the blower motor or compressor. Symptoms may include poor airflow, inconsistent temperatures, and higher energy bills. Solutions can range from simple DIY tasks like replacing air filters to more complex repairs that require a professional HVAC technician.
If the tune-up is not resolving the issue, it's best to have a professional HVAC technician inspect the system to diagnose and fix the underlying problem. Attempting complex repairs without the proper knowledge and tools can be dangerous and may end up costing more in the long run.