The answer to 'why is my air filter not turning on' is that the air filter itself does not actually turn on. The air filter is a passive component that is designed to remove dust, dirt, and other airborne particles from the air circulating through your HVAC system. If the air filter is not working, it is likely due to other issues with your HVAC system, not the filter itself.
Some common reasons why an air filter may appear to not be working include a clogged filter, a problem with the blower fan or motor, or issues with the air ducts or vents. If the filter is dirty and needs to be replaced, the air flow through the system will be reduced, which can make it seem like the filter is not working. You should check the filter and replace it if it is dirty or clogged. If replacing the filter does not resolve the issue, it is best to call a professional HVAC technician to diagnose and repair any underlying problems with your HVAC system.