A/C Pressure Cutoff Switch

An A/C pressure cut-off switch is used on all vehicles to interrupt operation of the A/C compressor in the event of high system discharge pressures. The A/C pressure cut-off switch is located in the condenser to evaporator tube between the A/C condenser core and the A/C evaporator core.

Dual Function
The A/C pressure cut-off switch has two sets of contacts. One electrical contact is normally closed.
- When compressor head pressure rises to 2860-3068 kPa (415-445 psi), the contacts open and interrupts operation of the A/C compressor.
- When head pressure drops to 1517-1930 kPa (220-280 psi), the contacts again close and allow operation of the A/C compressor.
- Shutting down compressor operation prior to the pressure relief valve set point of 3103 kPa (450 psi) ensures containment of the refrigerant in the A/C system.

The switch contains a second set of electrical contacts for the engine cooling fan motor which are normally open.
- When discharge line pressure reaches 1965-2172 kPa (285-315 psi), these contacts close and engage the engine cooling fan motor.
- When pressure drops to approximately 1724 kPa (250 psi), the contacts again open and the engine cooling fan motor is disengaged.