A/C Pressure Transducer: Operation

WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its connection to a fitting on the liquid line. The transducer will change its internal resistance in response to the pressures it monitors. The Power-train Control Module (PCM) provides a five 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 air conditioning compressor clutch and the radiator cooling fan to help optimize air conditioning system performance and to protect the system components from damage. When liquid line pressure rises above 3171 kPa (460 psi) or falls below 206 kPa (30 psi), the PCM turns the A/C compressor clutch off. The A/C pressure transducer input to the PCM will also prevent the air conditioning compressor clutch from engaging when ambient temperatures are below about 10° C (50° F) 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. The A/C pressure transducer is diagnosed using a DRBIII(R) scan tool. Refer to ELECTRONIC CONTROL MODULES .