No air coming out: Check if the vent damper is closed, or if the filter is clogged. Dirty filter = weak airflow.
• Weak airflow: Could be duct blockage, fan speed too low, or vent is too far from the unit.
• Vent making noise/whistling: Damper is half-closed or vent size is too small for the airflow.
• Water dripping from vent: Usually condensation + poor insulation, or the drain line is blocked.
• Bad smell: Mold/mildew in the duct or on the coil. Needs cleaning.