Compressor Cut-Off/Cycling Switchs

A/C Cycling Switch

The A/C cycling switch is mounted on a Schrader valve-type fitting on the side of the suction accumulator/drier in Aerostar vehicles, and on the top of the suction accumulator / drier in Ranger and Explorer vehicles. A valve depressor, located inside the threaded end of the A/C cycling switch, depresses the Schrader valve stem as the A/C cycling switch is mounted and allows the suction pressure inside the accumulator/drier housing to control operation. The electrical contacts are normally open when the suction pressure is at or below 169 kPa (24.5 psi); they will close when the suction pressure rises to approximately 300 kPa (43.5 psi) or above. Lower ambient temperatures (below 8°C or 46°F), during cold weather seasons, will also open the contacts due to the pressure/temperature relationship of the refrigerant in the system. The electrical contacts control the circuit to the A/C compressor A/C clutch field coil when the function selector lever is set for air conditioner operation. When the 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 contacts are open, the A/C compressor 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, when functioning properly, will control the pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing, which prevents icing and the blockage of airflow.