High Pressure Sensor / Switch: Description and Operation

Fig.23 High Pressure Cut Out Switch Location:

The high pressure cut out switch is a single pole, single throw, pressure actuated switch that is installed in a port into the discharge passage of the compressor. The high pressure cut out switch is located on the back cover of the compressor.

The high pressure cut out switch is a factory-calibrated unit. The switch cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The high pressure cut out switch monitors the pressure of the refrigerant leaving the compressor. The switch is connected in series electrically with the heater-A/C control blower and mode switches and the low pressure clutch cycling switch between ground and the Powertrain Control Module (PCM). The switch contacts open or close the path to ground, signaling the PCM to turn the compressor clutch ON and OFF. This prevents compressor operation when the discharge pressure exceeds about 3240 kPa (470 psi).