Discharge pressure (also called high side pressure or head pressure) is the pressure generated on the output side of a gas compressor in a refrigeration or air conditioning system. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface A gas compressor is a mechanical device that increases the Pressure of a Gas by reducing its Volume. Refrigeration is the process of removing Heat from an enclosed space or from a substance and moving it to a place where it is unobjectionable The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort. The discharge pressure is affected by several factors: size and speed of the condenser fan, condition and cleanliness of the condenser coil and the size of the discharge line. An extremely high discharge pressure coupled with an extremely low suction pressure is an indicator of a refrigerant restriction.