Pinpoint Test O: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON

Climate Control System

Pinpoint Test O: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON

Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information [1][2]Diagrams By Number.

Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

Under normal operation, when the A/C button is pressed, a message is sent from the Front Controls Interface Module (FCIM) over the Medium Speed Controller Area Network (MS-CAN) bus to the HVAC module. The HVAC module then sends an A/C request message over the MS-CAN (Medium Speed Controller Area Network) bus to the Instrument Cluster (IC) , then from the IC (Instrument Cluster) through the High Speed Controller Area Network (HS-CAN) bus to the PCM.

For all vehicles equipped with navigation, when MAX A/C is selected on the touch screen, the Audio Control Module (ACM) sends a message over the MS-CAN (Medium Speed Controller Area Network) bus to the HVAC module that MAX A/C has been selected.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Front Controls Interface Module (FCIM)

- PCM

- HVAC module

PINPOINT TEST O : THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C MODE ALWAYS COMMANDED ON

NOTE: Before carrying out the following test, diagnose any HVAC, PCM or IC (Instrument Cluster) DTCs.

O1 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_SW_AC) HVAC PID WITH THE A/C OFF

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: CC_SW_AC HVAC PID.

- Select PANEL press the A/C button (indicator off) on the HVAC controls.

Does the CC_SW_AC HVAC PID read Inactive?

Yes
GO to O2.

No
INSTALL a new Front Controls Interface Module (FCIM). TEST the system for normal operation.

O2 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: AC_REQ PCM PID.

- Select PANEL press the A/C button (indicator off) on the HVAC controls.

Does the AC_REQ PCM PID read OFF?

Yes
GO to O5.

No
GO to O3.

O3 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH HVAC MODULE DISCONNECTED

- Disconnect: HVAC Module C294A.

- Disconnect: HVAC Module C294B.

- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.

- Observe the AC_REQ PCM PID.

Does the AC_REQ PCM PID read OFF?

Yes
GO to O4.

No
GO to O5.

O4 CHECK THE HVAC MODULE CONNECTION

- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.


- Connect and correctly seat all the HVAC module connectors.

- Clear the DTCs.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new HVAC module. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

O5 CHECK THE PCM CONNECTION

- Disconnect all the PCM connectors.

- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.


- Connect and correctly seat all the PCM connectors.

- Clear the DTCs.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new PCM. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.