Grand Cherokee 2WD V8-4.7L VIN J (2004)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C PRESSURE TRANSDUCER
The A/C pressure transducer is installed on a fitting located on the refrigerant discharge line near the condenser. An internally threaded hex fitting
on the transducer connects it to the externally threaded Schrader-type fitting on the discharge line. A rubber O-ring seals the connection between
the transducer and the discharge line fitting. Three terminals within a molded plastic connector receptacle on the top of the transducer connect it to
the vehicle electrical system through a take out and connector of the headlamp and dash wire harness.
The A/C pressure transducer cannot be adjusted or repaired and if faulty or damaged, it must be replaced.
The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its connection to a fitting on the discharge
line. The transducer will change its internal resistance in response to the pressures it monitors. The Powertrain Control Module (PCM) provides a
five volt reference signal and a sensor ground to the transducer, then monitors the output voltage of the transducer on a sensor return circuit to
determine refrigerant pressure. The PCM is preprogrammed to respond to this and other sensor inputs by controlling the operation of the air
conditioning compressor clutch and the radiator cooling fan to help optimize air conditioning system performance and to protect the system
components from damage. The A/C pressure transducer input to the PCM will also prevent the air conditioning compressor clutch from engaging
when the ambient temperatures are below about 0.556 °C (33 °F) due to the pressure/temperature relationship of the refrigerant. The
Schrader-type valve in the liquid line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the
system. The A/C pressure transducer is diagnosed using the DRB III scan tool. Refer to the appropriate diagnostic information.
