Importance

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Abstract

An air conditioning system for automotive vehicles wherein the temperature and pressure of refrigerant at the outlet of the evaporator are detected, respectively, by a temperature sensor and a pressure sensor, and the flow rate of refrigerant within the refrigerating cycle is controlled to proper values corresponding to thermal load on the system, by controlling the opening of an expansion valve with a valve control means responsive to output signals from the above sensors. The pressure of refrigerant detected by the pressure sensor is converted by conversion means into a corresponding saturation temperature of the refrigerant. Determining means determines whether or not the refrigerant quantity is insufficient by comparing the difference between the refrigerant temperature and the corresponding saturation temperature of the refrigerant with a predetermined reference value. Indicator means indicates abnormality when the refrigerant quantity is determined to be insufficient. The valve control means causes disengagement of the electromagnetic clutch of the compressor to render the refrigerant compressor inoperative when the refrigerant quantity is determined to be insufficient.

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First Claim