The answer to 'air filter not working' is that the air filter in your HVAC system may be clogged, damaged, or installed incorrectly. A clogged air filter can restrict airflow, causing your HVAC system to work harder and less efficiently. Symptoms of a problem with the air filter include reduced air flow, higher energy bills, and a system that takes longer to reach the desired temperature.
In many cases, you can solve this issue by simply replacing the air filter. Be sure to use the correct size and type of filter recommended for your HVAC system. If the filter is damaged or the issue persists, you may need to call a professional HVAC technician to diagnose and repair the problem.