What causes the ac lines to frost over?

Frost on AC lines typically occurs due to low refrigerant levels, which reduce the pressure and temperature in the evaporator coil, causing moisture in the air to freeze. Poor airflow from dirty filters or blocked ducts can also contribute, as insufficient air circulation prevents proper heat exchange. Additionally, high humidity levels can exacerbate the issue, leading to condensation that freezes on the lines. Regular maintenance and checks can help prevent this problem.