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




Climate Control System

Pinpoint Test L: 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

Normal Operation

Under normal operation, when A/C is requested the HVAC module grounds a circuit to the Instrument Panel Cluster (IPC). The IPC then sends an A/C request through the High Speed Controller Area Network (HS-CAN) to the PCM.

- DTC 52 (A/C Select Drive Circuit/Performance) - This DTC sets when any of the following occur during a self-test:
- The module senses ground on the A/C request circuit when the circuit is not grounded by the HVAC module, indicating a short directly to ground.
- The module senses voltage on the A/C request circuit when the circuit is grounded by the HVAC module, indicating a short directly to voltage.
- The module senses no voltage on the A/C request circuit when the relay is not grounded by the HVAC module, indicating an open.

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

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

NOTE: Some PCM and Instrument Panel Cluster (IPC) DTCs may inhibit A/C operation. If any PCM or IPC DTCs are retrieved, diagnose those first. Refer to the PCM DTC Chart or the Instrument Panel Cluster (IPC) DTC Chart. PCM DTC Chart Instrument Panel Cluster (IPC) DTC Chart

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L1 CHECK THE HVAC MODULE FOR DTCs

- Ignition ON.
- Select OFF on the HVAC controls.
- CARRY OUT the HVAC module self-test.
- Check for HVAC DTCs retrieved during the self-test.
- Is DTC 52 present?

Yes
GO to L2.

No
GO to L3.

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L2 CHECK THE A/C REQUEST CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Disconnect: Instrument Panel Cluster (IPC) C220.
- Ignition ON.
- Measure the resistance between ground and HVAC module C228A-4, circuit CH434 (GY/YE), harness side.




- Is the resistance greater than 10,000 ohms?

Yes
GO to L8.

No
REPAIR circuit CH434 (GY/YE) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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L3 CHECK THE AIR CONDITIONING SWITCH (A/C_SWITCH) IPC PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- Monitor the A/C_SWITCH IPC PID
- Select PANEL and press the A/C button (indicator off) on the HVAC controls.
- Does the A/C_SWITCH IPC PID read INACTIVE?

Yes
GO to L4.

No
GO to L6.

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L4 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 and press the A/C button (indicator off) on the HVAC controls.
- Monitor the AC_REQ PCM PID
- Does the AC_REQ PCM PID read NO?

Yes
GO to L5.

No
GO to L7.

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L5 CHECK AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PCM PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select PANEL and press the A/C button (indicator off) on the HVAC controls.
- Monitor the ACC_CMD PCM PID
- Does the ACC_CMD PCM PID read OFF?

Yes
GO to L6.

No
GO to L7.

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L6 CHECK THE HVAC MODULE CONNECTION

- Disconnect all the HVAC module connectors.
- Inspect the HVAC module connectors for:

- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- 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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L7 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.
- 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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L8 CHECK THE IPC CONNECTION

- Disconnect all the IPC connectors.
- Inspect the IPC connectors for:

- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the IPC connectors.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new IPC. REFER to Instrumentation, Message Center, and Warning Chimes 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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