High Pressure Sensor / Switch: Description and Operation
A/C HIGH PRESSURE SWITCHDESCRIPTION
The A/C high pressure switch controls A/C compressor clutch engagement and disengagement when equipped with the 4.0L engine. The A/C high pressure switch is mounted on a fitting located on the A/C discharge line near the A/C compressor. The A/c high pressure switch turns off the A/C compressor if the refrigerant system pressure exceeds 3100 - 3375 kPa (450 - 490 psi)
The fitting for the A/C high pressure switch on the A/C discharge line is equipped with an O-ring seal and contains a Schrader-type valve, which allows the switch to be serviced without discharging the refrigerant system.
OPERATION
The A/C high pressure switch is electrically connected in series with the A/C low pressure switch between ground and the powertrain control module (PCM). The contacts in the A/C high pressure switch open and close causing the PCM to turn the A/C compressor clutch on and off. This prevents A/C compressor operation when the discharge line pressure approaches high levels, and also reduces electrical surging from A/C clutch engagement.
The A/C high pressure switch contacts open when the A/C discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The A/C high pressure switch contacts close when the A/C discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi).
The A/C high pressure switch is factory-calibrated and cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.