Pinpoint Test O: The Air Conditioning (A/C) is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test O: The Air Conditioning (A/C) is Inoperative
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
For vehicles equipped with navigation, when A/C button is pressed, a message is sent from the Front Controls Interface Module (FCIM) 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 Body Control Module (BCM), then from the BCM through the High Speed Controller Area Network (HS-CAN) bus to the PCM. When MAX A/C is selected on the touch screen, the Front Display Interface Module (FDIM) sends a message over the MS-CAN bus to the HVAC module that MAX A/C has been selected.
For vehicles not equipped with navigation, when A/C is requested, a message is sent from the HVAC module over the MS-CAN bus to the BCM, then from the BCM through the HS-CAN bus to the PCM.
Voltage is provided to the A/C clutch relay coil from Battery Junction Box (BJB) fuse 77 (10A) and switch contacts from Battery Junction Box (BJB) fuse 30 (10A). When A/C is requested and A/C line pressures allow, a ground is provided to the A/C clutch relay coil from the PCM, energizing the A/C clutch relay. When the PCM energizes the relay, voltage is supplied to the A/C compressor clutch field coil from the relay. Ground is supplied for the A/C compressor clutch field coil.
The evaporator temperature sensor is used for A/C compressor cycling. An accurate evaporator temperature is critical for compressor engagement. The PCM uses the temperature measurement to turn the A/C compressor off before the evaporator temperatures are cold enough to freeze the condensation on the evaporator core.
When an A/C request is received by the PCM, the A/C compressor clutch will only be engaged through the A/C clutch relay if all of the following conditions are met:
- The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
- The PCM does not detect excessively high engine coolant temperature.
- The PCM does not detect an ambient air temperature below -1°C (30°F).
- The PCM has not detected a Wide Open Throttle (WOT) condition.
- The HVAC module does not detect an evaporator discharge air temperature below 2°C (36°F).
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- A/C system discharged/low charge
- PCM
- HVAC module
- Front Controls Interface Module (FCIM)
- Evaporator temperature sensor
- A/C pressure transducer
- A/C compressor clutch field coil
- A/C clutch relay
- A/C compressor clutch air gap
PINPOINT TEST O: THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTE: Before carrying out the following test, diagnose any HVAC or PCM DTCs.
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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O1 CHECK THE A/C SYSTEM PRESSURE
- Ignition OFF.
- With the R-134a manifold gauge set connected, check the A/C system pressure.
- Is the A/C system pressure above 290 kPa (42 psi) ?
Yes
GO to O2.
No
CHECK the A/C system for leaks. REFER to Fluorescent Dye Leak Detection Fluorescent Dye Leak Detection or Electronic Leak Detection Electronic Leak Detection. RECHARGE the A/C system. REFER to Air Conditioning (A/C) System Recovery, Evacuation and Charging Air Conditioning (A/C) System Recovery, Evacuation and Charging. TEST the system for normal operation.
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O2 CHECK THE A/C PRESSURE SENSOR (ACP_PRESS) PCM PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- With the R-134a 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 PID similar?
Yes
GO to O3.
No
INSTALL a new A/C pressure transducer. TEST the system for normal operation.
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O3 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) HVAC PID
- Allow the vehicle exterior and interior to stabilize to the ambient temperature.
- Enter the following diagnostic mode on the scan tool: HVAC DataLogger.
- Monitor the EVAP_TEMP HVAC PID
- Does the EVAP_TEMP HVAC PID read similar to the ambient temperature?
Yes
For vehicles with navigation, GO to O5.
For vehicles without navigation, GO to O4.
No
INSTALL a new heater core and evaporator core housing. REFER to Climate Control Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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O4 CHECK THE (A/C) SWITCH (CC_SW_AC) HVAC PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: HVAC DataLogger.
- Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the CC_SW_AC HVAC PID.
- Does the CC_SW_AC HVAC PID read Active?
Yes
GO to O6.
No
GO to O17.
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O5 CHECK THE (A/C) SWITCH (CC_SW_AC) FCIM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: FCIM DataLogger .
- Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the CC_SW_AC FCIM PID.
- Does the CC_SW_AC FCIM PID read Active?
Yes
GO to O6.
No
INSTALL a new FCIM. REFER to Information and Entertainment Systems Front Controls Interface Module (FCIM). TEST the system for normal operation.
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O6 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the AC_REQ PCM PID.
- Does the AC_REQ PCM PID read YES?
Yes
GO to O7.
No
GO to O17.
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O7 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: PCM DataLogger.
- Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the ACC_CMD PCM PID.
- Does the ACC_CMD PCM PID read ON?
Yes
GO to O8.
No
GO to O18.
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O8 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY COIL
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between ground and the A/C clutch relay socket, circuit CBB77 (WH).
- Is the voltage greater than 10 volts?
Yes
GO to O9.
No
VERIFY Battery Junction Box (BJB) fuse 77 (10A) is OK. If OK, REPAIR circuit CBB77 (WH) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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O9 CHECK THE A/C CLUTCH RELAY
- Start the engine.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
- With the engine running, connect a 12-volt test light between A/C clutch relay socket, circuit CBB77 (WH) and A/C clutch relay socket, circuit CH302 (WH/BN).
- Does the test light illuminate?
Yes
GO to O12.
No
GO to O10.
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O10 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: PCM C1381B (5.0L, 6.2L).
- Disconnect: PCM C175B (3.7L).
- Disconnect: PCM C1551B (3.5L).
- Ignition ON.
For 3.7L, 5.0L and 6.2L
- Measure the voltage between ground and:
- For 3.7L, PCM C175B-12, circuit CH302 (WH/BN), harness side.
- For 5.0L and 6.2L, PCM C1381B-12, circuit CH302 (WH/BN), harness side.
For 3.5L
- For 3.5L, measure the voltage between ground and PCM C1551B-2, circuit CH302 (WH/BN), harness side.
- Is any voltage present?
Yes
REPAIR circuit CH302 (WH/BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to O11.
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O11 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
For 3.7L, 5.0L and 6.2L
- Measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and:
- For 3.7L, PCM C175B-12, circuit CH302 (WH/BN), harness side.
- For 5.0L and 6.2L, PCM C1381B-12, circuit CH302 (WH/BN), harness side.
For 3.5L
- For 3.5L, measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and PCM C1551B-2, circuit CH302 (WH/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O18.
No
REPAIR circuit 302 (WH/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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O12 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY SWITCH CONTACTS
- Measure the voltage between the A/C clutch relay socket, circuit SBB30 (BN/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to O13.
No
VERIFY Battery Junction Box (BJB) fuse 30 (10A) is OK. If OK, REPAIR circuit SBB30 (BN/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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O13 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: A/C Compressor Clutch Field Coil C100 .
- Measure the resistance between the A/C clutch relay socket, circuit CH401 (VT/WH) and A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O14.
No
REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
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O14 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Connect: A/C Clutch Relay.
- Ignition ON.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
- Measure the voltage between A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to O15.
No
INSTALL a new A/C clutch relay. TEST the system for normal operation.
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O15 CHECK THE GROUND AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Measure the resistance between A/C compressor clutch field coil C100-2, circuit GD123 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to O16.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
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O16 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 average greater than 0.65 mm (0.026 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. REFER to Climate Control Service and Repair. TEST the system for normal operation.
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O17 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.
- Enter the following diagnostic mode on the scan tool: Self-Test - HVAC Module.
- 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 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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O18 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.
- Clear the DTCs.
- Enter the following diagnostic mode on the scan tool: Self-Test - PCM.
- 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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