Perform the prior to using this diagnostic procedure.

Ignition voltage is supplied directly to the air conditioning (A/C) compressor clutch relay. The powertrain control module (PCM) or engine control module (ECM) controls the relay by grounding the A/C clutch relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. The driver has a fault line which is monitored by the PCM or ECM. When the PCM or ECM is commanding a component ON, the voltage of the control circuit should be near 0 volts. When the PCM or ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.

The PCM or ECM detects an open on the control circuit of the A/C compressor clutch relay.

A last test failed, or current DTC clears when the diagnostic runs and passes.

Schematic Reference

HVAC Schematics

Connector End View Reference

HVAC Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

1. Install a scan tool.
2. Ignition ON with the engine OFF, command the A/C Relay ON and OFF in the powertrain control module (PCM) or engine control module (ECM) Special Functions scan tool data list.
3. Feel/listen for the A/C relay to click. Observe the scan tool A/C Relay Circuit Status function or A/C relay solenoid turns on and off clicks.
4. Observe the scan tool, A/C Relay Circuit History.

1. Ignition OFF, disconnect the A/C Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal D, A/C Compressor Clutch Supply Voltage circuit and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the ignition circuit, coil feed circuit, terminal A and ground.

⇒	If the test lamp does not illuminate, test the igniton circuit for a short to ground or a open/high resisitance. If the circuit tests normal and ignition circuit fuse is open, test or replace the a/c compressor relay.

4. Verify that a test lamp illuminates between the B+ circuit, terminal C, switch feed circuit and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or a open/high resisitance. If the circuit tests normal and B+ circuit fuse is open, test or replace the a/c compressor relay.

5. Disconnect the harness connector at the A/C Clutch Coil.
6. Test for less than 1 ohm of resistance between the A/C Clutch Coil ground circuit terminal A and ground.

⇒	If greater than 1 ohm, test the ground circuit for an open/high resistance.

7. Connect the harness connector at the A/C Clutch Coil.
8. Connect a 3-amp fused jumper wire between the B+ circuit terminal C and control circuit terminal D of the A/C Clutch Relay. Verify the A/C Clutch Relay is activated.

⇒	If the A/C Clutch Relay does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C Clutch Relay.

9. Connect a test lamp between the A/C Clutch Relay ignition circuit terminal A, and the control circuit terminal B.
10. Command the A/C Relay output function 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 PCM/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 PCM/ECM.

11. If all circuits test normal, test or replace the A/C Clutch Relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Use the scan tool to clear the DTC's.
2. Operate the vehicle, recreating the conditions for running the DTC, observing for a possible reset of the DTC.