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

Climate Control System

Pinpoint Tests

Pinpoint Test Q: 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. Diagrams By Number

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

Normal Operation

For vehicles equipped with navigation, when 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 bus to the Body Control Module (BCM), then from the BCM through the High Speed Controller Area Network (HS-CAN) bus to the PCM. When MAX A/C is selected on the touch screen, the Front Display Interface Module (FDIM) sends a message over the MS-CAN bus to the HVAC module that MAX A/C has been selected.

For vehicles not equipped with navigation, when A/C is requested, a message is sent from the HVAC module over the MS-CAN bus to the BCM, then from the BCM through the HS-CAN bus to the PCM.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Front Controls Interface Module (FCIM)
- PCM
- HVAC module

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

NOTE: Before carrying out the following test, diagnose any HVAC or PCM DTCs.

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Q1 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select PANEL press the A/C button (indicator off) on the HVAC controls and monitor the AC_REQ PCM PID.
- Does the AC_REQ PCM PID read NO?

Yes
GO to Q6.

No
For vehicles with navigation, GO to Q3.

For vehicles without navigation, GO to Q2.

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Q2 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_SW_AC) HVAC PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: HVAC DataLogger.
- Select PANEL on the HVAC controls and monitor the CC_SW_AC HVAC PID.
- Does the CC_SW_AC HVAC PID read Inactive?

Yes
GO to Q4.

No
GO to Q5.

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Q3 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_SW_AC) FCIM PID WITH THE A/C OFF

- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Front Controls Interface Module (FCIM) DataLogger .
- Monitor the CC_SW_AC FCIM PID
- Select PANEL on the HVAC controls and monitor the CC_SW_AC FCIM PID.
- Does the CC_SW_AC FCIM PID read Inactive?

Yes
GO to Q4.

No
INSTALL a new Front Controls Interface Module (FCIM). REFER to Information and Entertainment Systems Front Controls Interface Module (FCIM). TEST the system for normal operation.

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Q4 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH HVAC MODULE DISCONNECTED

- Disconnect: HVAC Module - Electronic Manual Temperature Control (EMTC) C294A.
- Disconnect: HVAC Module - Dual Automatic Temperature Control (DATC) C228A/C2109A.
- Disconnect: HVAC Module - DATC C228B/C2109B.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Monitor the AC_REQ PCM PID
- Does the AC_REQ PCM PID read NO?

Yes
GO to Q5.

No
GO to Q6.

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Q5 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.
- Enter the following diagnostic mode on the scan tool: Self-Test - HVAC Module.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new HVAC module. REFER to Climate Control Service and Repair. 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.

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Q6 CHECK THE PCM CONNECTION

- Disconnect all the PCM connectors.
- Inspect the PCM connectors for:
- corrosion
- pushed-out terminals
- damaged terminals
- Connect and correctly seat all the PCM connectors.
- Clear the DTCs.
- Enter the following diagnostic mode on the scan tool: Self-Test - PCM.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. 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.

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