Dakota 2WD V8-4.7L VIN J (2005)
Refrigerant Pressure Sensor / Switch: Description and Operation
The A/C pressure transducer (1) is a switch that is installed on a fitting located on the A/C liquid line. An internally threaded fitting on the A/C pressure
transducer connects it to the externally threaded Schradertype fitting on the A/C 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 A/C liquid line.
The A/C pressure transducer will change its internal resistance in response to the pressures it monitors. A 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 A/C system.
The front control module (FCM) provides a five volt reference signal 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 FCM broadcasts a refrigerant pressure message to the PCM, which is
programmed to respond to the A/C pressure transducer and other sensor inputs by controlling the operation of the A/C compressor clutch 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 3172 kPa (460 psi) and re-engage the clutch when high side pressure drops below 1999 kPa (290 psi). The A/C pressure
transducer will also disengage the A/C compressor clutch if the high side pressure drops below 193 kPa (28 psi) and will re-engage the clutch when the
high side pressure rises above 234 kPa (34 psi). The A/C pressure transducer message 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 scan tool.
The A/C pressure transducer cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
