In what scenario would a frost form on the evaporator coil?

Frost forms on the evaporator coil primarily due to a combination of low temperature and moisture from the air. When air flows over the evaporator coil, the coil temperature must be sufficiently low to cool the air and create condensation. In a scenario where there is reduced airflow, the air passing over the coil does not circulate effectively, which allows the coil temperature to drop further than it should. This creates a temperature conducive to condensation, and when the moisture in the air comes into contact with the cold coil, it freezes, resulting in frost buildup.

If airflow is limited, the evaporation process is less efficient, which can lead to the coil becoming excessively cold and allowing frost to form. It's crucial to maintain adequate airflow over the evaporator coil to prevent frost accumulation, making this answer accurate in the context of understanding how evaporators work and the conditions that lead to frost formation.