A/C Cycling Switch and Pressure Cutoff Switch

A/C Cycling Switch
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. The contacts close when the suction pressure rises.For information regarding operating pressure specifications, refer to Specifications.
- When the A/C cycling switch contacts close, the signal to energize the A/C compressor clutch field coil is sent to the Powertrain Control Module (PCM). The PCM will then actuate the A/C control relay, energizing the A/C compressor.
- When the A/C cycling switch contacts open, the A/C compressor clutch field coil is de-energized and A/C compressor operation stops.
- 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 discharge the refrigerant system to remove the A/C cycling switch.

Pressure Cutoff Switch
The pressure cutoff switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.
- The pressure cutoff switch is mounted on a Schrader valve-type fitting on the high pressure side of the compressor manifold and tube assembly.
- A valve depressor, located inside the threaded end of the pressure cutoff switch, presses on the Schrader valve stem.
- This allows the pressure cutoff switch to monitor the compressor discharge pressure.
- When the compressor discharge pressure rises the switch contacts open, disengaging the A/C compressor. When the pressure drops the contacts close to allow operation of the A/C compressor.For information regarding operating pressure specifications, refer to Specifications.
- It is not necessary to discharge the refrigerant system to remove the pressure cutoff switch.