Low Pressure Sensor / Switch: Testing and Inspection

CAUTION: The work area must not be below 10°C (50°F) to test the compressor clutch circuit.

1. With gear selector in park or neutral and park brake set, start engine and allow to idle.
2. Raise hood and disconnect the Low Pressure Cut-Off (LPCO) switch connector boot.
3. Using a suitable jumper wire, jump across the terminals inside wire connector boot.
4. If the compressor clutch does not engage, the cycling clutch switch, wiring, relay, or fuse can be defective.
5. If clutch engages, connect manifold gauge set. Read low pressure gauge. At pressure above 97 kPa (14 psi) and above, LPCO switch will complete the clutch circuit. If the low pressure gauge reads below 172 kPa (25 psi), the system is low on refrigerant charge or empty due to a leak.
6. Install connector boot on switch and repeat step number 3. If the clutch does not engage, replace the LPCO switch.