Pinpoint Test K: The Air Conditioning (A/C) is Inoperative
Climate Control System
Pinpoint Test K: The Air Conditioning (A/C) is Inoperative
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
Under normal operation, when A/C is requested, the HVAC module 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 (Instrument Cluster) through the High Speed Controller Area Network (HS-CAN) bus to the PCM.
Ignition voltage is provided to the A/C clutch relay switch through circuit SBB30 (BN/RD). When the PCM energizes the relay, ignition voltage is supplied to the A/C clutch through circuit CH401 (VT/WH). Ground is supplied for the A/C clutch through circuit GD123 (BK/GY).
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).
The evaporator temperature sensor is used for A/C compressor cycling. An accurate evaporator temperature is critical for compressor engagement. The temperature measurement is used by the HVAC to turn off the A/C compressor when the evaporator temperatures are cold enough to freeze the condensation. This prevents ice blockage of airflow over the evaporator core.
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
- Battery Junction Box (BJB)
PINPOINT TEST K : 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 can cause wiring shorts or damage to modules. While carrying out diagnostics on BJB (Battery Junction Box) relays, have only one BJB (Battery Junction Box) relay removed at a time. Failure to follow these instructions may result in damage to the vehicle circuitry or to control modules.
NOTE: Before carrying out the following test, diagnose any HVAC, PCM or IC (Instrument Cluster) 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.
K1 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 K2.
No
INSTALL a new A/C pressure transducer. TEST the system for normal operation.
K2 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.
- Press the PANEL manual override button and press the A/C button (indicator on) on the HVAC module- Dual Automatic Temperature Control (DATC) or select MAX A/C mode on the HVAC module- Electronic Manual Temperature Control (EMTC).
Does the ACCS PCM PID read ON?
Yes
GO to K4.
No
GO to K3.
K3 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_AC) HVAC PID
- Enter the following diagnostic mode on the scan tool: CC_AC HVAC PID.
- Press and hold the A/C button on the HVAC module- DATC (Dual Automatic Temperature Control) or HVAC module- EMTC (Electronic Manual Temperature Control).
Does the CC_AC HVAC PID read DEPRESSED?
Yes
GO to K4.
No
GO to K11.
K4 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) HVAC PID
- Allow the vehicle exterior and interior to stabilize to an 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 K5.
No
INSTALL a new evaporator core. TEST the system for normal operation.
K5 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.
Does the WAC/ACCR PCM PID read ON?
Yes
GO to K6.
No
GO to K12.
K6 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Ignition ON.
- Press the PANEL and A/C manual override buttons on the HVAC module- DATC (Dual Automatic Temperature Control) or select MAX A/C on the HVAC module- EMTC (Electronic Manual Temperature Control).
- 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 K7.
No
GO to K9.
K7 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 K8.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
K8 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 . TEST the system for normal operation.
No
INSTALL a new A/C compressor clutch field coil. TEST the system for normal operation.
K9 CHECK THE A/C CLUTCH RELAY FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between the A/C clutch relay socket, circuit CBB30 (BN/RD) and ground.
Is the voltage greater than 10 volts?
Yes
GO to K10.
No
VERIFY BJB (Battery Junction Box) fuse 30 (10A) is OK. If OK, REPAIR circuit CBB30 (BN/RD) for an open. TEST the system for normal operation.
K10 CHECK CIRCUIT CH401 (VT/WH) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the A/C clutch relay socket, circuit CH401 (VT/WH), harness side and A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side.
Is the resistance less than 5 ohms?
Yes
CARRY OUT the A/C clutch relay component test. Component Tests
If the relay tests OK, GO to K12.
No
REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
K11 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. If the condition returns, GO to K12.
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.
K12 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.