High Pressure Sensor / Switch: Description and Operation

Rear A/C High Pressure Switch:

The rear A/C high pressure switch provides a signal to the rear A/C control module to control rear A/C compressor clutch engagement/ disengagement and, control rear A/C condenser cooling fan operation. The rear A/C control module will disengage the rear A/C clutch if the rear refrigerant system pressure exceeds approximately 2551 kPa (370 psi).

The rear A/C high pressure switch is mounted on a fitting located on the inlet tube of the rear A/C condenser.

The rear refrigerant system must be discharged prior to removing the rear A/C high pressure switch.

The contacts in the rear A/C high pressure switch open and close causing the rear A/C control module to turn the rear A/C clutch on and off. This prevents rear A/C compressor operation when the rear discharge line pressure approaches high levels, and also reduces electrical surging from rear A/C clutch engagement.

The rear A/C high pressure switch controls rear A/C condenser cooling fan operation by monitoring the rear discharge line pressure. When the rear discharge pressure rises above approximately 1900 to 2200 kPa (280 to 320 psi) the rear A/C condenser cooling fan will turn on. The rear condenser cooling fan will turn off when the rear discharge pressure drops to approximately 1600 kPa (235 psi).

The rear A/C high pressure switch contacts open when the rear discharge line pressure rises above approximately 3100 to 3375 kPa (450 to 490 psi). The rear A/C high pressure switch contacts close when the rear discharge line pressure drops to approximately 1860 to 2275 kPa (270 to 330 psi).

The rear A/C high pressure switch is factory-calibrated and cannot be adjusted or repaired and, if faulty or damaged, it must be replaced. Refer to the appropriate wiring information for complete HVAC wiring diagrams.