A/C Pressure Switch

The A/C cycling switch, located on the side of the suction accumulator/drier, monitors refrigerant pressure and sends this information to the Powertrain Control Module (PCM).

The A/C cycling switch internal electrical contacts control the electrical circuit to the A/C clutch. When the A/C cycling switch contacts are closed, the A/C clutch field coil is energized and the A/C clutch is engaged to drive the A/C compressor. When the A/C cycling switch contacts are open, the A/C clutch field coil is de-energized, the A/C clutch is disengaged and the A/C compressor does not operate.

The A/C cycling switch contacts will open when the suction pressure is approximately 158-165 kPa (23-24 psi). They will close when the suction pressure rises to approximately 317 kPa (46 psi) or above. Ambient temperatures that are below approximately 9°C (48°F), will also open the A/C cycling switch contacts, due to the pressure-to-temperature relationship of the refrigerant in the system.

When functioning properly, the A/C cycling switch will prevent the A/C evaporator core from icing, and prevent the blockage of airflow through the A/C evaporator core fins.