Dakota 4WD V8-4.7L (2009)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Pressure Transducer - Operation
OPERATION
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 Powertrain
Control Module (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 See: Powertrain Management/Computers and Control Systems/Testing and
Inspection/Diagnostic Trouble Code Tests and Associated Procedures
The A/C pressure transducer cannot be adjusted or repaired and must be replaced if inoperative or damaged.
