Compare airflow and coil symptoms
Weak cooling or icing does not by itself prove that refrigerant is low. A restricted filter, blocked airflow, dirty coil, or control problem can affect coil temperature and operation. For central equipment, the duct path may also be relevant; ductless systems have their own indoor-unit airflow and coil conditions. Inspection findings help determine whether the fault is within the air path or requires refrigerant-circuit diagnosis.
