Refrigerant Pressure Sensor / Switch: Description and Operation

Fig.15 A/C Pressure Transduser:

A/C PRESSURE TRANSDUCER
This vehicle is equipped with an a/c pressure transducer. This transducer is screwed onto a fitting on the liquid line between the condenser and the high side refrigerant system service port.

The main function of the a/c pressure transducer is to disengage the compressor clutch when the refrigerant system high pressures are too high. The PCM senses a voltage from the transducer and converts it to a pressure. Based on this pressure, the PCM will disengage the clutch at 460 psi and re-engage the clutch at 290 psi. The a/c heater control also uses the pressure value to operate the auto-recirculation function for improved a/c performance under extreme conditions.