The A/C clutch is controlled by the A/C cycling switch (19E561) and the A/C pressure cut-off switch, which are connected in series. The A/C cycling switch is mounted on the suction accumulator/drier (19C836), and the A/C pressure cut-off switch is mounted in the discharge line at the A/C condenser.
The A/C cycling switch closes when the pressure on the low side of the system reaches approximately 276-324 kPa (40-47 psi). The A/C cycling switch opens when the pressure drops to approximately 163-175 kPa (23.5-25.5 psi), disengaging the A/C clutch. In ambient temperatures below -1° C (30° F), the A/C cycling switch will not allow compressor operation because of low system pressures.
The A/C pressure cut-off switch is used to interrupt A/C clutch operation in the event of high system discharge pressures. The A/C pressure cut-off switch is a single-function switch that controls A/C clutch engagement. When compressor head pressures rise to approximately 2896 kPa (420 psi), the contacts open, disengaging the A/C clutch. When the pressures drop to approximately 1724 kPa (250 psi), the contacts close to allow A/C clutch operation.
This problem can be caused by low refrigerant charge. Check with a manifold gauge set and temperature pressure chart.
The cycling switch is replaceable and there is a Schrader valve on the accumulator port so you do not lose your system charge when replacing. It screws on/off. It is available at any auto parts store. It protects the compressor from low pressure which can be caused by a loss of refrigerant and subsequent lack of lubrication and prevents evaporator freeze up. Replace the switch. It is about $10. The high presure switch is about $25.
