Circuit/System Testing
WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
- Disconnect the A/C CLUTCH relay.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
- If the test lamp illuminates, test the control circuit for a short to voltage.
- Verify that a test lamp illuminates between the ignition circuit terminal 85 and ground.
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the relay.
- Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal for a short to ground.
- Disconnect the harness connector at the A/C compressor clutch.
- Test for less than 1.0 ohm between the A/C compressor clutch ground circuit terminal B and ground
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect the harness connector at the A/C compressor clutch.
- Connect a 10A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the A/C compressor clutch is activated.
- If the A/C compressor clutch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C compressor clutch.
- Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
- Command the A/C relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the A/C CLUTCH relay.