High Pressure Cutoff Switch
WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The high pressure cutoff switch, also referred to as the dual function pressure switch, is used to interrupt A/C compressor operation and/or the electric engine cooling fan in the event of high system discharge pressures.
- The high pressure cutoff switch is mounted on a Schrader-type valve fitting on the high pressure side of the condenser to evaporator line.
- A valve depressor, located inside the threaded end of the dual function pressure switch, is used to monitor the compressor discharge pressure.
- It is not necessary to discharge the refrigerant system to remove the dual function pressure switch.
- The high pressure cutoff switch has 2 sets of contacts. One electrical contact is normally closed.
- When the compressor discharge pressure rises to approximately 3,000-3,275 kPa (435-475 psi), the switch contacts open, signaling the PCM to disengage the A/C compressor.
- When the pressure drops to approximately 1,517-1,931 kPa (220-280 psi), the contacts close to allow operation of the A/C compressor.
The switch contains a second set of electrical contacts used for high-speed fan control.
- When the compressor discharge pressure reaches approximately 2,137-2,344 kPa (310-340 psi), these contacts close and send a signal to the PCM to engage the high-speed fan control.
- When the pressure drops to approximately 1,655-2,137 kPa (240-310 psi), the contacts again open and the high speed fan control is disengaged.