A/C High Pressure Switch
WARNING: This page is about a different car, the 2003 GMC Safari and 2003 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
The A/C system is protected by two pressure switches. The A/C high pressure switch is a two wire normally open switch. The A/C high pressure switch opens the A/C request signal when the A/C line pressure exceeds 3240 kPa (470 psi) + or - 20 psi. This prevents the A/C compressor from operating.