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

Climate Control System

Pinpoint Tests

Pinpoint Test N: 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

Under normal operation, when the A/C is requested, an A/C request message is sent from the HVAC module over the Medium Speed Controller Area Network (MS-CAN) bus to the Instrument Panel Cluster (IPC), then from the IC through the High Speed Controller Area Network (HS-CAN) bus to the PCM.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM
- HVAC module

PINPOINT TEST N: 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 DTCs first.

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N1 CHECK THE A/C 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 OFF?

Yes
GO to N2.

No
GO to N4.

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N2 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 NO?

Yes
GO to N5.

No
GO to N3.

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N3 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH HVAC MODULE DISCONNECTED

- Ignition OFF.
- Disconnect: HVAC Module C228.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: AC_REQ PCM PID.
- Observe the AC_REQ PCM PID.
- Does the AC_REQ PCM PID read NO?

Yes
GO to N4.

No
GO to N5.

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N4 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. REFER to Climate Control Heating Ventilation Air Conditioning (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.

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N5 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.

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