The answer to 'air filter making noise' is that a noisy air filter is usually caused by the filter being clogged or improperly installed. A clogged filter can create resistance and vibration, leading to a rattling or humming noise. Improper installation, such as the filter being misaligned or not fitting snugly, can also cause it to vibrate and make noise.
In most cases, the solution is simply to replace the air filter with a new one. Make sure to choose the correct size and type of filter for your HVAC system. If the noise persists after replacing the filter, it may be due to other issues like a problem with the blower motor or ductwork. In these cases, it's best to call a professional HVAC technician to diagnose and fix the problem.