A/C Pressure Switch

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

Electrical A/C cycling switch contacts, located inside the A/C cycling switch, 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 electrical A/C cycling switch contacts will open when the suction pressure is approximately 169 kPa (24.5 psi). They will close when the suction pressure rises to approximately 276-324 kPa (40-47 psi) or above. Ambient temperatures that are below approximately 9°C (48°F) will prevent the suction pressure from closing the A/C cycling switch contacts.

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