High Pressure Sensor / Switch: Testing and Inspection

High Pressure Switch

The high pressure switch cuts off the electrical power supply to the magnetic clutch when refrigerant pressure rises above the setting.

This switch may operate when the flow of air across the condenser is obstructed by the dead leaves, newspaper, etc. blocking the condenser surface, or the refrigerant system is overcharged.

To Test the High Pressure Switch (Engine Off)
1. Jump the wire leads.
2. Press the A/C switch and blower switch ON.
3. Momentarily turn the ignition switch on (do not crank the engine), and listen for the clutch engaging.
4. If the clutch does not engage, the air flow thermostat, low pressure switch, coolant temperature switch, or fuse may be faulty. Correct fault.
5. If clutch engages, connect the manifold gauge set and read pressure. At any pressure of 2,010 kPa (291.5 psi), the switch must be off.
6. If the clutch does not engage, replace the switch.