The answer to 'why is my air filter making loud noise' is that a clogged or dirty air filter can cause the blower fan to work harder, leading to increased noise and vibration. This is a common issue that can be easily resolved.
When the air filter becomes obstructed with dust, dirt, and other debris, it restricts the airflow through the HVAC system. This forces the blower fan to work overtime to push air through the filter, which can result in a loud, rattling, or humming noise. Additionally, the increased strain on the fan motor can lead to further issues if the problem is not addressed.