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Home >> Mitsubishi >> 2008 >> Raider 4WD V6-3.7L >> Repair and Diagnosis >> Heating and Air Conditioning >> Refrigerant Pressure Sensor / Switch >> Description and Operation
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Refrigerant Pressure Sensor / Switch: Description and Operation

TRANSDUCER - A/C PRESSURE

DESCRIPTION




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 Schrader-type 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.

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 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 must be replaced if found inoperative or damaged.
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