Pinpoint Test L: The Air Conditioning (A/C) Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test L: 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
Under normal operation, for Dual Automatic Temperature Control (DATC) systems, when A/C is requested, the HVAC module - DATC sends an A/C request message over the Medium Speed Controller Area Network (MS-CAN) bus to the Instrument Cluster (IC), then from the IC through the High Speed Controller Area Network (HS-CAN) bus to the PCM.
Under normal operation, for manual climate control systems, when A/C is requested, a voltage is supplied to the PCM on the A/C request PCM input.
The PCM also receives a ground from the A/C cycling switch when pressures are sufficient to close the switch. Ground is provided to the A/C cycling switch.
Voltage is provided to the A/C clutch relay switch. When the PCM energizes the relay, voltage is supplied to the A/C clutch from the relay. Ground is supplied for the A/C clutch.
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 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 PCM does not detect excessively low refrigerant pressure from the A/C cycling switch.
The A/C cycling switch is used for A/C compressor cycling. The A/C cycling switch is used by the PCM to turn off the A/C compressor when the refrigerant pressure is low enough to make the evaporator temperatures cold enough to freeze the condensation. The A/C pressure transducer is used to turn off the A/C compressor when the refrigerant pressure is to high. Excessively high refrigerant pressure can damage the A/C compressor.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- PCM
- HVAC module - DATC
- Function selector switch (manual climate control systems)
- A/C cycling switch
- A/C compressor clutch field coil
- A/C control relay
- A/C clutch air gap
PINPOINT TEST L: THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTE: Before carrying out the following test, diagnose any HVAC, PCM or IC 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.
NOTE: The ambient temperature, as indicated by the DATC display, must be over 6°C (43°F). If the ambient temperature display is inaccurate, GO to Symptom Chart - Climate Control Systems. Symptom Chart - Climate Control Systems
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L1 CHECK THE AIR CONDITIONING COMPRESSOR CYCLING SWITCH (ACCS) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Place the function selector switch in the MAX A/C position or press the PANEL and A/C manual override buttons on the HVAC module - DATC.
- Does the ACCS PCM PID read ON?
Yes
GO to L5.
No
For manual climate control systems, GO to L2.
For DATC systems, GO to L4.
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L2 CHECK PCM FOR A/C SIGNAL VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175B.
- Ignition ON.
- Measure the voltage between ground and PCM C175B-15, circuit CH443 (GN/OG), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to L16.
No
GO to L3.
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L3 CHECK CIRCUIT CH443 (GN/OG) FOR AN OPEN
- Ignition OFF.
- Disconnect: Function Selector Switch C294C.
- Measure the resistance between climate control assembly C294C-9, circuit CH443 (GN/OG), harness side and PCM C175B-15, circuit CH443 (GN/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
REPAIR circuit CH443 (GN/OG) for an open. TEST the system for normal operation.
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L4 CHECK THE AIR CONDITIONING SWITCH STATUS (AC_SEL_SW) HVAC PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: AC_SEL_SW HVAC PID.
- Press the PANEL and press and hold the A/C manual override buttons on the HVAC module - DATC.
- Does the AC_SEL_SW HVAC PID read A/C?
Yes
GO to L16.
No
GO to L15.
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L5 CHECK THE AIR CONDITIONING COMPRESSOR DIAGNOSTIC SWITCH (ACDS1) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: ACDS1 PCM PID.
- Place the function selector switch in the MAX A/C position or press the PANEL and A/C manual override buttons on the HVAC module - DATC.
- Does the ACDS1 PCM PID read ENABLE?
Yes
GO to L9.
No
GO to L6.
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L6 CHECK THE A/C CYCLING SWITCH INPUT
- Ignition OFF.
- Disconnect: PCM C175B.
- Measure the resistance between ground and PCM C175B-16, circuit CH423 (YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to L16.
No
GO to L7.
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L7 CHECK CIRCUIT CH423 (YE) FOR AN OPEN
- Disconnect: A/C Cycling Switch C130.
- Measure the resistance between A/C cycling switch C130-1, circuit CH423 (YE), harness side and PCM C175B-16, circuit CH423 (YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to L8.
No
REPAIR circuit CH423 (YE) for an open. TEST the system for normal operation.
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L8 CHECK THE A/C CYCLING SWITCH
- Ignition OFF.
- Measure the resistance between the A/C cycling switch terminals.
- Is the resistance less than 5 ohms?
Yes
REPAIR circuit GD113 (BK/YE) for an open. TEST the system for normal operation.
No
INSTALL a new A/C cycling switch. TEST the system for normal operation.
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L9 CHECK THE AIR CONDITIONING CLUTCH (WAC/ACCR) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: WAC/ACCR PCM PID.
- Place the function selector switch in the MAX A/C position or press the PANEL and A/C manual override buttons on the HVAC module - DATC.
- With the engine running, does the WAC/ACCR PCM PID read ON?
Yes
GO to L10.
No
GO to L16.
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L10 CHECK CIRCUIT SBB35 (BU/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Control Relay.
- Ignition ON.
- Measure the voltage between ground and A/C control relay socket pin 3, circuit SBB35 (BU/RD).
- Is the voltage greater than 10 volts?
Yes
GO to L11.
No
VERIFY the Battery Junction Box (BJB) fuse 35 (10A) is OK. If OK, REPAIR circuit SBB35 (BU/RD) for an open. TEST the system for normal operation.
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L11 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Connect: A/C Control Relay.
- Disconnect: A/C Compressor Clutch Field Coil C1110.
- Ignition ON.
- With the engine running, measure the voltage between ground and A/C compressor clutch field coil C1110-1, circuit CH401 (VT/WH) (4.0L) or CH401 (GY/WH) (4.6L), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to L13.
No
GO to L12.
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L12 CHECK CIRCUIT CH401 (VT/WH) OR CIRCUIT CH401 (GY/WH) FOR AN OPEN
- Ignition OFF.
- Connect: A/C Control Relay.
- Measure the resistance between A/C control relay socket pin 5, circuit CH401 (VT/WH) (4.0L) or CH401 (GY/WH) (4.6L) and A/C compressor clutch field coil C1110-1, circuit CH401 (VT/WH) (4.0L) or CH401 (GY/WH) (4.6L), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new A/C control relay. TEST the system for normal operation.
No
REPAIR circuit CH401 (VT/WH) (4.0L) or CH401 (GY/WH) (4.6L) for an open. TEST the system for normal operation.
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L13 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 C1110-2, circuit GD120 (BK/GN) (4.0L) or GD120 (BK) (4.6L), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to L14.
No
REPAIR circuit GD120 (BK/GN) (4.0L) or GD120 (BK) (4.6L) for an open. TEST the system for normal operation.
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L14 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 field coil. 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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L15 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.
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L16 CHECK THE PCM CONNECTION
- Disconnect all the PCM connectors.
- Inspect the 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.
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