Car A/C Evaporator Pressure Regulator System
The evaporator pressure regulator type system (see illustration) is used only on Chrysler Corporation vehicles with a twin-cylinder compressor. Unlike the suction throttling valve (STV) and valves-in-receiver (VIR) units, which are mounted in-line, but outside the compressor, the evaporator control valve is located within the low pressure side of the compressor. The EPR or evaporator temperature regulator (ETR) valve senses the pressure of the incoming refrigerant and opens or closes to regulate the flow of refrigerant through the compressor, thus controlling the evaporator temperature. This system also uses an expansion valve located at the inlet side of the evaporator (the configuration of this valve varies in newer applications). To clean or inspect the EPR valve, simply remove the inlet connection from the compressor.