RAM 3500 Chassis Cab Truck 2WD L6-6.7L DSL Turbo (2010)
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 discharge line
and its internal resistance changes in response to the pressures it monitors. The Engine Control Module (ECM) provides a five volt reference signal and a
sensor ground to the A/C pressure transducer, then monitors the output voltage of the transducer on a sensor return circuit to determine refrigerant
pressure. The ECM is programmed to respond to this and other sensor inputs by controlling the operation of the A/C clutch and the cooling fan to help
optimize A/C system performance and to protect the system components from damage. The ECM will disengage the A/C 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 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). If the refrigerant pressure rises above 1655 kPa (240 psi), the ECM will actuate the cooling fan. The A/C pressure transducer signal to
the ECM also prevents the A/C clutch from engaging when ambient temperatures are below about 10° C (50° F), due to the pressure/temperature
relationship of the refrigerant.
A Schrader-type valve in the discharge line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the
A/C system.
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.
