Durango 4WD V8-5.9L VIN Z (1998)
Low Pressure Sensor / Switch: Description and Operation
Low Pressure Cut-Off Switch
Low Pressure Cut-off Switch
The low pressure cut-off switch is located on the suction line jumper near the dash panel in the engine compartment. The switch is screwed onto a
fitting on the suction line jumper that contains a Schrader-type valve, which allows the switch to be serviced without discharging the refrigerant
system. The suction line jumper fitting is equipped with an O-ring to seal the switch connection.
The low pressure cut-off switch is connected in series electrically with the high pressure cut-off switch, the electronic cycling clutch switch and the
heater-A/C controls, between ground and the Powertrain Control Module (PCM). The switch contacts open and close causing the PCM to turn the
compressor clutch on and off. This helps to regulate the refrigerant system pressure and protects the compressor from damage due to loss of
refrigerant and refrigerant oil.
The low pressure cut-off switch contacts are open when the suction pressure is about 68.9 kPa (10 psi) or lower. The switch contacts will close
when the suction pressure rises to about 89.6 to 186.1 kPa (13 to 27 psi) or above. Lower ambient temperatures, below about -1° C (30° F) , will
also cause the switch contacts to open. This is due to the pressure/temperature relationship of the refrigerant in the system.
The low pressure cut-off switch is a factory-calibrated unit. It cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
