Method and apparatus for detecting low refrigerant charge

摘要

In an air conditioning system, thermistors measure evaporator inlet and outlet temperatures and compressor body temperature. When the differential between inlet and outlet temperatures is below a first threshold and the compressor temperature is above a second threshold, very low refrigerant charge is indicated and the compressor is turned off. Also, if compressor temperature reaches a critical value, the compressor is turned off regardless of the temperature differential across the evaporator.