Refrigerant Pressure Sensor / Switch: Description and Operation

A/C PRESSURE SWITCHES

The A/C system is protected by two A/C pressure switches.
- A/C low pressure switch
- A/C high pressure switch

The A/C high pressure switch interrupts the A/C request signal when the A/C line pressure is more than a predetermined value. The A/C low pressure switch interrupts the A/C low pressure switch signal when the A/C line pressure is less than or more than a predetermined value. When the powertrain control module (PCM) stops receiving the required signals, the A/C compressor clutch relay control circuit is no longer grounded, disengaging the A/C compressor clutch. The A/C compressor clutch is disengaged under the following conditions:
- A/C low pressure switch is less than 124 kPa (18 psi).
- A/C low pressure switch is more than 338 kPa (49 psi).
- A/C high pressure switch is more than 2896 kPa (420 psi).