Pinpoint Test H: The Air Conditioning (A/C) Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test H: The Air Conditioning (A/C) is Inoperative
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:
- Fuse
- Wiring, terminals or connectors
- PCM
- HVAC module
- A/C evaporator discharge temperature sensor
- A/C pressure transducer
- A/C compressor clutch field coil
- A/C control relay
- A/C clutch air gap
PINPOINT TEST H: THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTICE: It is important to install relays in their correct position in the Battery Junction Box (BJB). Installing a relay incorrectly may cause wiring shorts or damage to modules. While carrying out diagnostics on BJB relays, have only one BJB relay removed at a time. Failure to follow these instructions may result in damage to the vehicle circuitry or to control modules.
NOTE: Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retrieved, diagnose those first. Refer to the PCM DTC Chart. PCM DTC Chart
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.
NOTE: Before carrying out the following test, check that the A/C system pressure is above 290 kPa (42 psi). If the pressure is below 290 kPa (42 psi), refer to Fluorescent Dye Leak Detection Fluorescent Dye Leak Detection.
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H1 CHECK THE A/C PRESSURE SENSOR (ACP_PRESS) PCM PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ACP_PRESS PCM PID.
- With the manifold gauge set connected, compare the pressure readings of the manifold gauge set and the ACP_PRESS PCM PID.
- Are the pressure values of the manifold gauge set and the ACP_PRESS PCM PID similar?
Yes
GO to H2.
No
INSTALL a new A/C pressure transducer. TEST the system for normal operation.
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H2 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) HVAC PID
- Allow the vehicle exterior and interior to stabilize to an ambient temperature above 16°C (60°F).
- Enter the following diagnostic mode on the scan tool: EVAP_TEMP HVAC PID.
- Does the EVAP_TEMP HVAC PID read similar to the ambient temperature?
Yes
GO to H3.
No
INSTALL a new A/C evaporator discharge temperature sensor. TEST the system for normal operation.
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H3 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_AC) HVAC PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: CC_AC HVAC PID.
- Press and hold the A/C request button on the HVAC module.
- Does the CC_AC HVAC PID read DEPRESSED?
Yes
GO to H4.
No
GO to H10.
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H4 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: AC_REQ PCM PID.
- Select MAX A/C on the HVAC module.
- Does the AC_REQ PCM PID read YES?
Yes
GO to H5.
No
GO to H11.
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H5 CHECK THE AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: ACC_CMD PCM PID.
- Does the ACC_CMD PCM PID read ON?
Yes
GO to H6.
No
GO to H11.
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H6 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Ignition ON.
- Select MAX A/C on the HVAC module.
- Measure the voltage between ground and A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to H7.
No
CARRY OUT the A/C clutch relay component test. If the relay tests OK, GO to H9.
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H7 CHECK THE GROUND AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Measure the resistance between ground and A/C compressor clutch field coil C100-2, circuit GD120 (BK/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to H8.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
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H8 CHECK THE A/C COMPRESSOR CLUTCH AIR GAP
- Measure the A/C compressor clutch air gap at 3 equally spaced locations between the clutch hub and the A/C compressor clutch pulley.
- Is the A/C compressor clutch air gap greater than 0.6 mm (0.024 in) ?
Yes
ADJUST the A/C compressor clutch gap. REFER to Air Conditioning (A/C) Clutch Air Gap Adjustment Adjustments. TEST the system for normal operation.
No
INSTALL a new A/C compressor clutch field coil. TEST the system for normal operation.
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H9 CHECK THE A/C CLUTCH RELAY FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between ground and the A/C clutch relay socket, circuit SBB13 (GY/RD).
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
No
VERIFY BJB fuse 13 (10A) is OK. If OK, REPAIR circuit SBB13 (GY/RD) for an open. TEST the system for normal operation.
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H10 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.
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H11 CHECK THE PCM MODULE 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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