The answer to 'tune-up not working' is that there can be several common causes, including dirty air filters, low refrigerant levels, issues with the thermostat, or problems with the compressor or other components. Symptoms may include poor airflow, inadequate cooling, and higher energy bills.
In many cases, a tune-up by a professional HVAC technician can help resolve these issues. They will thoroughly inspect the system, clean components, check refrigerant levels, and make any necessary adjustments or repairs. While some basic maintenance like changing air filters can be done DIY, more complex tune-up tasks are best left to the professionals to ensure the job is done properly and safely.