Component Tests and General Diagnostics

The work area temperature must not be below 10 °C (50 °F) to test the compressor clutch circuit.
1. With gear selector in neutral, the park brake set, start engine and allow to idle.
2. Raise hood and disconnect DPCO 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 evaporator probe switch, wiring, relay, or fuse can be defective. Refer to Wiring Diagrams.
5. If clutch engages, connect manifold gauge set. Read low pressure gauge. At pressure above 196 to 248 kPa (28.4 to 36 psi) and above, DPCO switch will complete the clutch circuit. If the low pressure gauge reads below 193 kPa (28 psi), the system is low on refrigerant charge or empty due to a leak.
6. Install connector boot on switch and repeat Step 3. If the clutch does not engage, replace the DPCO switch.