1993 Chevrolet Cavalier Owner's Manual - Page 110

Comfort Controls & Audio Systems Air Conditioning (CONX:) VENT Use on pleasant days when little heating or cooling is needed, to direct outside air into the vehicle. In this setting, the air flow is through the instrument panel outlets. B/L (Bi-Level): Use on cool, but sunny days. This setting brings inthe outside air, but directs it in ways. Air is two directed to the upper portion of your body through the instrument panel outlets, and tothe lower portion of your body through the heater ducts. At times, this temperature difference may be more apparent than others. HTR (Heater): Use this setting to direct most of the airflow through the heater ducts, and some through the windshield defroster vents. If you have the optional engine block heater and useit during cold weather, 0°F (-18°C) or lower, your heating system will more quickly provideheat because the engine coolant is already warmed. See the Index under Engine Block Heater. BLEND: This setting divides the air flow equally between the heater ducts and the windshield defroster vents. DEF (Defrost):This setting directs most air through the windshield defroster vents, and some through the heater ducts.