Avenger L4-2.4L (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 discharge line.
The internal resistance of the A/C pressure transducer changes in response to the pressures it monitors. The Totally Integrated Power Module (TIPM)
provides a five volt reference signal and a sensor ground to the A/C pressure transducer. The TIPM then monitors the output voltage of the transducer on
a sensor return circuit to determine refrigerant pressure and sends a message to the Powertrain Control Module (PCM) or Engine Control Module (ECM)
(depending on engine application) over the Controller Area Network (CAN) C BUS. The PCM/ECM is programmed to respond to this and other sensor
inputs by controlling the operation of the swash plate within the A/C compressor and the radiator cooling fan to help optimize A/C system performance
and to protect the system components from damage. The PCM adjusts the swash plate to nearly a zero degree angle (low compressor displacement) when
high side pressure rises above 3130 kPa (454 psi) and readjusts the swash plate to a greater angle (higher compressor displacement) when high side
pressure drops below 1999 kPa (290 psi). The A/C pressure transducer also reduces the swash plate angle if the high side pressure drops below 200 kPa
(29 psi) and will increase the swash plate angle when the high side pressure rises above 234 - 262 kPa (34 - 38 psi). When the refrigerant pressure rises
above 1655 kPa (240 psi) the PCM will actuate the cooling fan.
A Schrader-type valve in the A/C 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.
