A/C Pressure Transducer
A/C pressure transducer may also be referred to as A/C pressure sensor. The A/C pressure transducer is a switch that is installed on a fitting located on the refrigerant liquid line between the filter-drier and the expansion valve in the right rear corner of the engine compartment. See Fig 1 . An internally threaded hex fitting on the transducer connects it to the externally threaded Schrader-type fitting on the liquid line. A rubber "O" ring seals the connection between the transducer and the liquid line fitting. Three terminals within a molded plastic connector receptacle on the top of the transducer connects it to the vehicle electrical system through a take out and connector of the headlight and dash wiring harness. The A/C pressure transducer cannot be adjusted or repaired. If faulty or damaged, the transducer must be replaced.
The A/C pressure transducer monitors the pressures in the high side of the refrigerant system. The transducer will change its internal resistance in response to the pressures it monitors. The PCM provides a 5.0-volt reference signal and a sensor ground to the transducer, then monitors the output voltage of the transducer on a sensor return circuit to determine refrigerant pressure. The PCM is programmed to respond to this 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 A/C pressure transducer input to the PCM will also prevent the A/C compressor clutch from engaging when ambient temperatures are below 50°F (10°C) due to the pressure/temperature relationship of the refrigerant. The 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 system.