Pinpoint Test J: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON
Climate Control System
Pinpoint Tests
Pinpoint Test J: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON
Refer to Wiring Diagrams Set 54, Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, when A/C is requested a message is sent over the Medium Speed Controller Area Network (MS-CAN) bus to the instrument cluster, then from the instrument cluster through the High Speed Controller Area Network (HS-CAN) bus to the PCM. Battery voltage for the A/C clutch relay contacts is provided through circuit SBB13 (GY/RD). When the PCM receives the request, the A/C pressure transducer does not indicate excessive pressure and the evaporator temperature sensor does not indicate a low evaporator temperature, it energizes the relay sending battery voltage 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 J: THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C MODE ALWAYS COMMANDED ON
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.
-------------------------------------------------
J1 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_AC) HVAC PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: CC_AC HVAC PID.
- Does the CC_AC HVAC PID read DEPRESSED?
Yes
GO to J4.
No
GO to J2.
-------------------------------------------------
J2 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 OFF on the HVAC module.
- Does the AC_REQ PCM PID read YES?
Yes
GO to J5.
No
GO to J3.
-------------------------------------------------
J3 CHECK AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PCM PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: ACC_CMD PCM PID.
- Does the ACC_CMD PCM PID read ON?
Yes
GO to J5.
No
GO to J4.
-------------------------------------------------
J4 CHECK THE MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- 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.
-------------------------------------------------
J5 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.
-------------------------------------------------