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 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, for vehicles equipped with next generation navigation, when A/C button is pressed, a message is sent from the Front Controls Interface Module (FCIM) module 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 PCM. When MAX A/C is selected on the touch screen, the Audio Control Module (ACM) sends a message over the MS-CAN bus to the HVAC module that MAX A/C has been selected.
For vehicles not equipped with next generation navigation, when A/C is requested, a message is sent from the HVAC module over the MS-CAN bus to the PCM.
Ignition voltage is provided to the A/C clutch relay switch through circuit SBB24 (VT/RD). When the PCM energizes the relay, ignition voltage is supplied to the A/C clutch through circuit CH401 (VT/WH). Ground is supplied for the A/C clutch through circuit GD120 (BK/GN).
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 PCM or Instrument Cluster (IC) DTCs.
NOTE: When disconnecting and reconnecting the pressure transducer electrical connector, make sure that the connector-locking device is in place and that the locking device and connector are correctly and fully seated.
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N1 CHECK THE ACCS PCM PID WITH THE A/C OFF
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Select PANEL press the A/C button (indicator off) on the HVAC module.
- Does the ACCS PCM PID read ON?
Yes
If the vehicle is equipped with next generation navigation, GO to N3.
If the vehicle is not equipped with next generation navigation, GO to N2.
No
GO to N6.
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N2 CHECK THE (A/C) SWITCH (CC_SW_AC) HVAC PID WITH THE A/C OFF
- 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 module.
- Does the CC_SW_AC HVAC PID read Inactive?
Yes
GO to N6.
No
GO to N5.
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N3 CHECK THE A/C INDICATOR WITH THE A/C OFF
NOTE: Before carrying out this test step, be sure all other FCIM button functions are operational. If all other buttons operate correctly, continue with this test step. If multiple buttons are inoperative and DTC U0010:88 is not present, install a new FCIM. Test the system for normal operation. If DTC U0010:88 is present, diagnose the DTC first.
- Select PANEL press the A/C button (indicator off) on the HVAC module.
- Does the A/C indicator turn off when the A/C button is pressed?
Yes
GO to N5.
No
GO to N4.
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N4 CHECK THE MAX A/C OPERATION
NOTE: Before carrying out this test step, be sure all other ACM touch screen functions are operational. If all other touch screen functions operate correctly, continue with this test step. If multiple touch screen functions are inoperative and DTC U0010:88 is not present, install a new ACM. Test the system for normal operation. If DTC U0010:88 is present, diagnose the DTC first.
- Select MAX A/C on the next generation navigation screen.
- Does the A/C turn off when MAX A/C is selected?
Yes
INSTALL a new FCIM. TEST the system for normal operation.
No
GO to N5.
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N5 CHECK THE MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module On-Demand Self Test. Alternate Diagnostic Methods - HVAC Module
- Operate the system.
- Does the concern return?
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.
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N6 CHECK THE PCM CONNECTION
- Clear the DTCs.
- Disconnect all of the PCM connectors.
- Check for:
- corrosion.
- pushed-out connectors.
- incorrectly seated connector.
- Connect and correctly seat all of the PCM connectors.
- Operate the system.
- Does the concern return?
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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