The answer to 'why is my HVAC system not working' is that there could be several common causes, including a thermostat issue, a problem with the air filter, a refrigerant leak, or a malfunctioning component. Symptoms may include the system not turning on, poor airflow, strange noises, or inconsistent temperatures.
For minor issues, you may be able to troubleshoot and fix the problem yourself, such as checking the thermostat settings, replacing the air filter, or resetting the system. However, for more complex problems or anything involving the refrigerant system, it's best to call in a professional HVAC technician to properly diagnose and repair the issue.