Liberty 2008 HVAC Refrigerant Pressure Sensor Description - Page 848
Refrigerant Pressure Sensor / Switch: Description and Operation
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. The powertrain control module (PCM) or the
engine control module (ECM) (depending on engine application) 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/ECM
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/ECM will disengage the
A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 psi). The A/C pressure transducer input to the
PCM/ECM also prevents the A/C compressor 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 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.
The A/C pressure transducer cannot be adjusted or repaired and it must be replaced if found inoperative or damaged.
