What physical symptom indicates a dirty filter during the cooling process?

Frost formation is a key indicator of a dirty filter during the cooling process. When the filter becomes clogged with dirt and debris, it restricts airflow through the system. This reduced airflow prevents the evaporator coil from absorbing heat efficiently, leading to lower temperatures in the coil. As the coil gets colder than usual due to insufficient airflow, the moisture in the air can freeze on the coil, resulting in frost or ice buildup. This can eventually lead to the system overheating and potentially causing further damage if not addressed.

In contrast, reduced humidity, increased air temperature, and noise from the unit can stem from various other issues within an HVAC system and are less specifically linked to a dirty filter's impact on cooling performance. Frost formation is a direct result of the inefficiencies caused by the airflow restriction, highlighting the importance of regular filter maintenance for optimal system operation.