A/C Cycling Switch
WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The A/C cycling switch is mounted on a Schrader valve-type fitting on the top of the suction accumulator.
- A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem.
- This allows the suction pressure inside the suction accumulator to control the operation of the A/C cycling switch.
- The electrical switch contacts open when the suction pressure drops to 145-165 kPa (21-24 psi).
- The contacts close when the suction pressure rises to 200-317 kPa (29-46 psi).
- When the A/C cycling switch contacts close, the signal to energize the A/C clutch is sent to the powertrain control module (PCM) which energizes the A/C relay and supplies B+ voltage to the A/C clutch field coil.
- When the A/C cycling switch contacts open, the A/C clutch field coil is de-energized and compressor operation stops.
- The A/C cycling switch controls the A/C evaporator core pressure at a point where the plate/fin surface temperature is maintained slightly above freezing.
- This prevents icing of the A/C evaporator core and blockage of airflow.
- It is not necessary to discharge the refrigerant system to remove the A/C cycling switch.