A/C Pressure Transducer
WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The A/C pressure transducer communicates the compressor discharge pressure to the PCM. The PCM will interrupt A/C compressor operation in the event that the A/C pressure transducer indicates excessively high system discharge pressures. It is also used to sense low charge conditions. If the pressure is below a predetermined value for a given ambient temperature, the PCM will not allow the clutch to engage.