Pacifica V6-3.8L VIN L (2005)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Pressure Transducer
The A/C pressure transducer is a switch that is installed on a fitting located on the liquid line. An internally threaded hex fitting on the A/C pressure
transducer connect it to the externally threaded Schrader-type fitting on the liquid line. A rubber O-ring seals the connection between the A/C pressure
transducer and the liquid line fitting.The A/C pressure transducer is connected to the vehicle electrical system by a molded plastic connector with three
terminals.
The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its connection to a fitting on the liquid line. The
A/C pressure transducer will change its internal resistance in response to the pressures it monitors. 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 powertrain control module (PCM) provides a five volt reference signal and a sensor ground to the A/C pressure transducer, then monitors the output
voltage of the A/C pressure transducer on a sensor return circuit to determine refrigerant pressure. The PCM is programmed to respond to the A/C
pressure transducer and other sensor inputs by controlling the operation of the A/C compressor clutch and the radiator cooling fan to help optimize A/C
system performance and to protect the system components from damage. The PCM will disengage the A/C compressor clutch when high side pressure
rises above 3082 kPa (447 psi) and re-engage the clutch when high side pressure drops below 2937 kPa (426 psi). The A/C pressure transducer will
also disengage the A/C compressor clutch if the high side pressure drops below 110 kPa (16 psi) and will re-engage the clutch when the high side
pressure rises above 221 kPa (32 psi). If the refrigerant pressure rises above 1655 kPa (240 psi), the PCM will actuate the cooling fan. The A/C
pressure transducer input to the PCM will also prevent the A/C compressor clutch from engaging when ambient temperatures are below about 4.5° C (40
° F) due to the pressure/temperature relationship of the refrigerant.
The A/C pressure transducer is diagnosed using a DRBIII(R) scan tool.
The A/C pressure transducer cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.