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 Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, when A/C is requested the HVAC module then 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.
Voltage is provided to the A/C clutch relay switch contacts. When the PCM energizes the relay, voltage is supplied to the A/C compressor clutch field coil. The A/C compressor clutch field coil is grounded.
The evaporator discharge air temperature sensor is used for A/C compressor cycling. An accurate evaporator discharge air temperature is critical for compressor engagement. The temperature measurement is used by the PCM to turn off the A/C compressor when the evaporator temperatures are cold enough to freeze the condensation.
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 A/C pressure transducer does not indicate excessively low or high refrigerant pressure. Refer to Specifications.
- The PCM does not detect excessively high engine coolant temperature.
- The PCM does not detect an ambient air temperature below 0°C (32°F).
- The PCM has not detected a Wide Open Throttle (WOT) condition.
- The HVAC module does not detect an evaporator discharge air temperature below 0.6°C (33°F).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- PCM
- HVAC module
- A/C evaporator discharge air 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
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.
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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 ambient temperature.
- 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 evaporator discharge air temperature sensor. REFER to Climate Control Service and Repair. 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.
CHECK the A/C clutch diode. INSTALL a new diode if necessary. 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. REFER to Climate Control Service and Repair. 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 Battery Junction Box (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
- Inspect the 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. REFER to Climate Control Heating Ventilation Air Conditioning (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 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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