Pinpoint Test J: The Air Conditioning (A/C) is Inoperative
Climate Control System
Pinpoint Test J: The Air Conditioning (A/C) is Inoperative
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
Normal Operation
When A/C is requested the HVAC module grounds a circuit to the Instrument Panel Cluster (IPC). The IPC (Instrument Panel Cluster) then sends an A/C request through the High Speed Controller Area Network (HS-CAN) to the PCM.
Voltage is provided to the A/C clutch relay coil and switch contacts. 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 clutch from the relay. Ground is supplied for the A/C clutch.
The evaporator discharge air 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 temperature is 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 only engages 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).
- DTC 52 (A/C Select Drive Circuit/Performance)- This DTC sets when any of the following occur during a self-test:
- The module senses ground on the A/C request circuit when the circuit is not grounded by the HVAC module, indicating a short directly to ground.
- The module senses voltage on the A/C request circuit when the circuit is grounded by the HVAC module, indicating a short directly to voltage.
- The module senses no voltage on the A/C request circuit when the relay is not grounded by the HVAC module, indicating an open.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- A/C system discharged/low charge
- PCM
- HVAC module
- IPC (Instrument Panel Cluster)
- Evaporator discharge air temperature sensor
- A/C pressure transducer
- A/C compressor clutch field coil
- A/C clutch relay
- A/C compressor clutch air gap
PINPOINT TEST J : THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTE: Some PCM and Instrument Panel Cluster (IPC) DTCs may inhibit A/C operation. If any PCM or IPC (Instrument Panel Cluster) DTCs are retrieved, diagnose those first. Refer to the PCM DTC Chart PCM DTC Chart or the Instrument Panel Cluster (IPC) DTC Chart Instrument Panel Cluster (IPC) DTC Chart.
J1 CHECK THE HVAC MODULE FOR DTCs
- Ignition ON.
- CARRY OUT the HVAC module self-test.
- Check for HVAC DTCs retrieved during the self-test.
IS DTC 52 present?
Yes
GO to J19.
No
GO to J2.
J2 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 J3.
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.
J3 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 PCM PID similar?
Yes
GO to J4.
No
INSTALL a new A/C pressure transducer. TEST the system for normal operation.
J4 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) Instrument Panel Cluster (IPC) PID
- Allow the vehicle exterior and interior to stabilize to the ambient temperature.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- Monitor the EVAP_TEMP IPC (Instrument Panel Cluster) PID
Does the EVAP_TEMP IPC (Instrument Panel Cluster) PID read similar to the ambient temperature?
Yes
GO to J5.
No
GO to J21
J5 CHECK THE AIR CONDITIONING SWITCH (A/C_SWITCH) IPC (Instrument Panel Cluster) PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- Monitor the A/C_SWITCH IPC (Instrument Panel Cluster) PID
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
Does the A/C_SWITCH IPC (Instrument Panel Cluster) PID read ACTIVE?
Yes
GO to J7.
No
GO to J6.
J6 CHECK THE A/C REQUEST TO THE IPC (Instrument Panel Cluster)
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Ignition OFF.
- Disconnect: Instrument Panel Cluster (IPC) C220.
- Ignition ON.
- Connect a 12-volt test light between IPC (Instrument Panel Cluster) C220-4, circuit CBP21 (BU/GY), harness side and IPC (Instrument Panel Cluster) C220-12, circuit CH434 (GY/YE), harness side.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
Does the test light illuminate?
Yes
GO to J24.
No
GO to J22.
J7 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 and press the A/C button (indicator on) on the HVAC controls.
- Monitor the AC_REQ PCM PID
Does the AC_REQ PCM PID read YES?
Yes
GO to J8.
No
GO to J24.
J8 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 and press the A/C button (indicator on) on the HVAC controls.
- Monitor the ACC_CMD PCM PID
Does the ACC_CMD PCM PID read ON?
Yes
GO to J9.
No
GO to J23.
J9 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Start the engine.
- 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 J10.
No
GO to J13.
J10 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 J11.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
J11 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL
- Measure the resistance between the A/C compressor clutch field coil C100 terminals, component side.
Is the resistance between 2 and 5 ohms?
Yes
GO to J12.
No
INSTALL a new A/C compressor clutch field coil. TEST the system for normal operation.
J12 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL FOR A SHORT TO GROUND
- Measure the resistance between the A/C compressor clutch field coil C100 terminals, component side and ground.
Is the resistance greater than 10,000 ohms?
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.
J13 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY COIL
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Start the engine.
- Measure the voltage between A/C clutch relay socket pin 1, circuit CBP02 (GN) and ground.
Is the voltage greater than 10 volts?
Yes
GO to J14.
No
VERIFY Central Junction Box (CJB) fuse 2 (10A) is OK. If OK, REPAIR circuit CBP02 (GN) 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 Electrical Diagrams.
J14 CHECK THE A/C CLUTCH RELAY
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning or equivalent. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- 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 pin 1, circuit CBP02 (GN) and A/C clutch relay socket pin 2, circuit CH302 (WH/BN).
Does the test light illuminate?
Yes
GO to J17.
No
GO to J15.
J15 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175B.
- Ignition ON.
- Measure the voltage between ground and PCM C175B-25, circuit CH302 (WH/BN), harness side.
Is any voltage present?
Yes
REPAIR circuit CH302 (WH/BN) for a short to voltage. TEST the system for normal operation.
No
GO to J16.
J16 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between A/C clutch relay socket pin 2, circuit CH302 (WH/BN) and PCM C175B-25, circuit CH302 (WH/BN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to J23.
No
REPAIR circuit CH302 (WH/BN) for an open. TEST the system for normal operation.
J17 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY SWITCH CONTACTS
- Measure the voltage between ground and the A/C clutch relay socket pin 3, circuit SBB30 (RD).
Is the voltage greater than 10 volts?
Yes
GO to J18.
No
VERIFY Battery Junction Box (BJB) fuse 30 (10A) is OK. If OK, REPAIR circuit SBB30 (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 Electrical Diagrams.
J18 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between A/C clutch relay socket pin 5, 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
INSTALL a new A/C clutch relay. TEST the system for normal operation.
No
REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
J19 CHECK THE A/C REQUEST CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Disconnect: Instrument Panel Cluster (IPC) C220.
- Ignition ON.
- Measure the voltage between ground and HVAC module C228A-4, circuit CH434 (GY/YE), harness side.
Is any voltage present?
Yes
REPAIR circuit CH434 (GY/YE) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to J20.
J20 CHECK THE A/C REQUEST CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between HVAC module C228A-4, circuit CH434 (GY/YE), harness side and IPC (Instrument Panel Cluster) C220-12, circuit CH434 (GY/YE), harness side.
Is the resistance less than 5 ohms?
Yes
GO to J22.
No
REPAIR circuit CH434 (GY/YE) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
J21 CHECK THE EVAPORATOR TEMPERATURE AIR TEMPERATURE SENSOR
- Ignition OFF.
- Disconnect: Evaporator Discharge Air Temperature Sensor C296.
- CARRY OUT the Evaporator Discharge Air Temperature Sensor component test Component Tests.
Did the evaporator discharge air temperature sensor test OK?
Yes
GO to J24.
No
INSTALL a new evaporator discharge air temperature sensor. TEST the system for normal operation.
J22 CHECK THE HVAC MODULE CONNECTION
- Disconnect all the HVAC module connectors.
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- 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.
J23 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.
- 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.
J24 CHECK THE IPC (Instrument Panel Cluster) CONNECTION
- Disconnect all the IPC (Instrument Panel Cluster) connectors.
- Inspect the IPC (Instrument Panel Cluster) connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the IPC (Instrument Panel Cluster) connectors.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new IPC (Instrument Panel Cluster). 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.