The answer to 'HVAC repair not working' is that there can be several common causes, including issues with the thermostat, air filters, electrical components, refrigerant levels, or the compressor. Symptoms may include the system not turning on, poor airflow, strange noises, or inconsistent temperatures.
For simple problems like a dirty air filter or thermostat issues, homeowners may be able to troubleshoot and fix the problem themselves. However, for more complex issues involving electrical systems or refrigerant, it's generally best to call in a professional HVAC technician to diagnose and repair the problem properly and safely.