The answer to 'HVAC system not working' is that there can be several common causes, including a tripped circuit breaker, clogged air filters, refrigerant leaks, or issues with the thermostat or other components. Symptoms may include the system not turning on, poor airflow, or inconsistent temperatures throughout the home.
For minor issues like a tripped breaker or dirty air filter, homeowners can often troubleshoot and fix the problem themselves. However, for more complex problems involving refrigerant leaks, compressor failures, or electrical issues, it's best to call in a professional HVAC technician. Attempting DIY repairs on these systems can be dangerous and may void the warranty.