A/C Signal: Description and Operation

The pressure cycling switch, located on the low pressure tube at the right rear of the engine compartment, interrupts power to the compressor clutch relay if the pressure drops below a specified limit. When the A/C system refrigerant level is low, the compressor clutch will cycle frequently &/or remain "OFF" for longer than normal periods. The BCM can detect this condition by monitoring the voltage in the circuit between the low pressure cycling switch and the compressor clutch relay. The BCM will set a trouble code if this condition is detected.