Refrigerant Pressure Sensor / Switch: Description and Operation

The low refrigerant pressure switch is located in the low pressure refrigerant line. The switch when pressurized is closed and allows the compressor clutch relay to energize, feeding battery voltage to the compressor clutch coil.

If the pressure drops below kPa 55-90 (8-13 PSI) the switch opens and cuts off voltage to the clutch. There is a circuit to the Body Control Module (BCM) which monitors the state of the switch for diagnostic purposes.