A/C Cycling Switch and A/C Pressure Cutoff Switch

A/C Cycling Switch
The A/C cycling switch is mounted on a Schrader valve-type fitting on 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 or low side pressure to control the operation of the A/C cycling switch.
- The electrical switch contacts open when the suction pressure drops to 152-193 kPa (22-28 psi).
- The contacts close when the suction pressure rises to 276-324 kPa (40-47 psi).
- When the A/C cycling switch contacts close, the A/C clutch field coil is energized.
- When the A/C cycling switch contacts open, the A/C clutch field coil is deenergized and 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.







A/C Pressure Cutoff Switch
The A/C pressure cutoff switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.
- The A/C pressure cutoff switch is mounted on a Schrader valve-type fitting on the A/C compressor to condenser discharge line.
- A valve depressor, located inside the threaded end of the A/C pressure cutoff switch, presses on the Schrader valve stem.
- This allows the A/C pressure cutoff switch to monitor the compressor discharge pressure.
- When the compressor discharge pressure rises to approximately 2896 kPa (420 psi), the switch contacts open, disengaging the A/C compressor.
- When the pressure drops to approximately 1724 kPa (250 psi), the contacts close to allow operation of the A/C compressor.
- It is not necessary to discharge the refrigerant system to remove the A/C pressure cutoff switch.