Air Conditioning (A/C) Cycling Switch
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. 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 suction accumulator.
- The A/C Cycling switch is used by the PCM to indicate if A/C refrigerant low side pressures are within operating specifications for A/C compressor operation. A 12 volt signal is supplied by the SJB when the ignition is in the run position to the cycling switch.
- 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. The contacts close when the suction pressure rises.
- When the A/C Cycling switch contacts close, the 12 volt signal is sent to the PCM indicating A/C refrigerant low side pressures are within operating specifications for A/C compressor operation.
- When the A/C cycling switch contacts open, the 12 volts signal to the PCM is interrupted, indicating A/C refrigerant pressures are below operating specifications for A/C compressor operation.
- The A/C cycling switch will control the evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing.
- This prevents icing of the evaporator core and blockage of airflow.
- It is not necessary to recover the refrigerant system to remove the A/C cycling switch.