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

Climate Control System

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

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 Body Control Module (BCM), then from the BCM (Body Control Module) 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 (Instrument Cluster) DTCs first.

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.

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.

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.

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. 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.

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.