A/C Low Pressure Switch
WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
The A/C low pressure switch protects the A/C system from a low pressure condition that could damage the A/C compressor or cause evaporator icing. The Powertrain Control Module (PCM) applies the A/C low pressure switch control signal. The switch will open when the A/C low side pressure reaches 24-26 psi (1.68-1.82 kg/cm2 ). This prevents the A/C compressor from operating. The switch will then close when A/C low pressure side reaches 38-42 psi (2.6-3.0 kg/cm2 ). This allows the A/C compressor to turn back on.