Patent ID: 7472557

Claim:
Apparatus for automatically adjusting the volume of refrigerant charge in an air conditioning system having a compressor, a condenser, an expansion device and a evaporator fluidly connected in serial refrigerant flow relationship comprising: a plurality of sensors for respectively sensing a plurality of selected temperature and pressure conditions of the system; memory means for storing representative values for said sensed conditions; memory means for storing algorithms for computing charge level indicators as a function of said stored representative values; memory means for storing optimal charge level indicators for at least one particular system; comparison means for comparing said computed charge level indicators with said optimal charge level indicators to obtain a difference value; a source of refrigerant fluidly connected to said system by way of at least one valve; and valve activating means for controlling said at least one valve in response to said difference value to change the level of refrigerant in said system wherein said plurality of selected temperature and pressure conditions includes either the combination of outdoor air temperature and condenser liquid refrigerant temperature or a combination of condenser liquid temperature and condenser coil temperature.