Pinpoint Test G: The Air Conditioning (A/C) is Inoperative
Climate Control System
Pinpoint Test G: The Air Conditioning (A/C) is Inoperative
Refer to Wiring Diagrams Set 54, Manual Climate Control System for schematic and connector information. Electrical Diagrams
Normal Operation
When the A/C switch is pressed, a ground is provided to the Instrument Cluster (IC) A/C switch input. When the IC (Instrument Cluster) receives this ground, it sends an A/C request message through the High Speed Controller Area Network (HS-CAN) bus to the PCM and an A/C request message through the Medium Speed Controller Area Network (MS-CAN) to the Generic Electronic Module (GEM).
When the GEM (Generic Electronic Module) receives the A/C request message from the IC (Instrument Cluster), it provides a ground for the A/C switch indicator. Voltage is provided to the indicator. When the GEM (Generic Electronic Module) provides ground the indicator illuminates.
Voltage is provided to the A/C clutch relay (switch contacts). 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 only engages 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 GEM (Generic Electronic Module) does not detect excessively low refrigerant pressure from the A/C cycling switch.
- 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 A/C cycling switch is used for A/C compressor cycling. The A/C cycling switch is normally closed (sufficient pressure) and supplies ground to the GEM (Generic Electronic Module). When the A/C cycling switch opens (low pressure) it removes the ground to the GEM (Generic Electronic Module). The GEM (Generic Electronic Module) sends this status to the IC (Instrument Cluster) through the MS-CAN (Medium Speed Controller Area Network), then from the IC (Instrument Cluster) to the PCM through the HS-CAN (High Speed Controller Area Network). This tells the PCM to turn on the A/C compressor when pressures are high enough and also turn off the A/C compressor before the refrigerant pressure is low enough to make the evaporator temperatures cold enough to freeze the condensation.
- DTC B1858 (Climate Control A/C Pressure Switch Circuit Failure)- This DTC sets when the GEM (Generic Electronic Module) detects the an open A/C cycling switch or circuit when the A/C is commanded on during an on-demand self-test.
- DTC B294A (Air Conditioning Switch Short to Battery)- This DTC sets when the GEM (Generic Electronic Module) detects excessive voltage or no voltage drop when the GEM (Generic Electronic Module) applies ground to the A/C switch indicator circuit during an on-demand self-test, indicating an open circuit or short to voltage on the circuit.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- A/C system discharged/low charge
- A/C switch
- A/C pressure transducer
- A/C cycling switch
- A/C compressor clutch field coil
- A/C clutch relay
- A/C compressor clutch air gap
- GEM (Generic Electronic Module)
- IC (Instrument Cluster)
- PCM
PINPOINT TEST G : THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTE: Before carrying out the following test, diagnose any PCM, GEM (Generic Electronic Module) 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.
G1 CHECK A/C INDICATOR OPERATION
- Start the engine.
- Place the blower motor switch in the lowest position.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button (indicator on).
Does the A/C indicator illuminate?
Yes
GO to G10.
No
GO to G2.
G2 CHECK AIR CONDITIONING SWITCH (AC_SW) IC (Instrument Cluster) PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: IC (Instrument Cluster) DataLogger.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button and monitor the AC_SW IC (Instrument Cluster) PID.
Does the AC_SW IC (Instrument Cluster) PID read YES?
Yes
GO to G6.
No
GO to G3.
G3 CHECK THE A/C SWITCH GROUND
- Ignition OFF.
- Disconnect: A/C Switch C2891.
- Measure the resistance between A/C switch C2891-2, circuit 91-FA13 (BK/OG), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to G4.
No
REPAIR circuit 91-FA13 (BK/OG) for an open. TEST the system for normal operation.
G4 CHECK AIR CONDITIONING SWITCH AC_SW IC (Instrument Cluster) PID WITH THE A/C SWITCH BYPASSED
- Start the engine.
- Enter the following diagnostic mode on the scan tool: IC (Instrument Cluster) DataLogger.
- With the engine running, connect a fused jumper between A/C switch C2891-2, circuit 91-FA13 (BK/OG), harness side and A/C switch C2891-6, circuit 15S-FA13 (GN/RD), harness side and monitor the AC_SW IC (Instrument Cluster) PID.
Does the AC_SW IC (Instrument Cluster) PID read YES?
Yes
INSTALL a new A/C switch. TEST the system for normal operation.
No
GO to G5.
G5 CHECK THE A/C SWITCH INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: IC (Instrument Cluster) C220A.
- Measure the resistance between function A/C switch C2891-6, circuit 15S-FA13 (GN/RD), harness side and IC (Instrument Cluster) C220A-23, circuit 15S-FA13 (GN/RD), harness side.
Is the resistance less than 5 ohms?
Yes
GO to G28.
No
REPAIR circuit 15S-FA13 (GN/RD) for an open. TEST the system for normal operation.
G6 CHECK THE VOLTAGE AT THE A/C SWITCH
- Ignition OFF.
- Disconnect: A/C Switch C2891.
- Ignition ON.
- Measure the voltage between A/C switch C2891-1, circuit 15-FA9 (GN/BK), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to G7.
No
VERIFY the Central Junction Box (CJB) fuse 152 (7.5A) is OK. If OK, REPAIR circuit 15-FA9 (GN/BK) for an open. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Electrical Diagrams
G7 CHECK THE A/C SWITCH INDICATOR
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.
- Start the engine.
- Connect a 12-volt test light between A/C switch C2891-1, circuit 15-FA9 (GN/BK), harness side and A/C switch C2891-5, circuit 91S-FA9 (BK/GN), harness side.
- With the engine running, momentarily connect a fused jumper between A/C switch C2891-2, circuit 91-FA13 (BK/OG), harness side and A/C switch C2891-6, circuit 15S-FA13 (GN/RD), harness side.
Does the test light illuminate?
Yes
INSTALL a new A/C switch. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to G8.
G8 CHECK THE A/C SWITCH INDICATOR SWITCHED GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: GEM (Generic Electronic Module) C201C.
- Measure the resistance between A/C switch C2891-5, circuit 91S-FA9 (BK/GN), harness side and GEM (Generic Electronic Module) C201C-19, circuit 91S-FA9 (BK/GN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to G9.
No
REPAIR circuit 91S-FA9 (BK/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
G9 CHECK THE A/C SWITCH INDICATOR SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between A/C switch C2891-5, circuit 91S-FA9 (BK/GN), harness side and ground
Is any voltage present?
Yes
REPAIR circuit 91S-FA9 (BK/GN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to G27.
G10 CHECK THE A/C LOW PRESSURE CYCLING SWITCH (AC_LOWSW) PCM PID
- Start the engine.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button and monitor the AC_LOWSW PCM PID.
Does the AC_LOWSW PCM PID read Closed?
Yes
GO to G14.
No
GO to G11.
G11 CHECK A/C LOW PRESSURE CYCLING SWITCH (AC_LOWSW) PCM PID WITH THE LOW CHARGE PROTECTION SWITCH BYPASSED
- Ignition OFF.
- Disconnect: A/C Cycling Switch C1081.
- Connect a fused jumper between A/C cycling switch C1081-1, circuit 7-FA11 (YE), harness side and A/C cycling switch C1081-4, circuit 91-FA11 (BK/YE), harness side.
- Start the engine.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button and monitor the AC_LOWSW PCM PID.
Does the AC_LOWSW PCM PID read Closed?
Yes
INSTALL a new A/C cycling switch. TEST the system for normal operation.
No
GO to G12.
G12 CHECK THE A/C CYCLING SWITCH GROUND
- Ignition OFF.
- Measure the resistance between ground and A/C cycling switch C1081-4, circuit 91-FA11 (BK/YE), harness side.
Is the resistance less than 5 ohms?
Yes
GO to G13.
No
REPAIR circuit 91-FA11 (BK/YE) for an open. TEST the system for normal operation.
G13 CHECK THE A/C CYCLING SWITCH INPUT CIRCUIT FOR AN OPEN
- Disconnect: GEM (Generic Electronic Module) C201E.
- Measure the resistance between function A/C cycling switch C1081-1, circuit 7-FA11 (YE), harness side and GEM (Generic Electronic Module) C201E-23, circuit 7-FA11 (YE), harness side.
Is the resistance less than 5 ohms?
Yes
GO to G27.
No
REPAIR circuit 7-FA11 (YE) for an open. TEST the system for normal operation.
G14 CHECK THE A/C PRESSURE SENSOR (ACP_PRESS) PCM PID
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- 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 G15.
No
INSTALL a new A/C pressure transducer. TEST the system for normal operation.
G15 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID
- Start the engine.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button (indicator on) and monitor the AC_REQ PCM PID.
Does the AC_REQ PCM PID read YES?
Yes
GO to G18.
No
GO to G16.
G16 CHECK IC (Instrument Cluster) BLOWER SWITCH INPUT
NOTE: DTC C1779 sets when ground is present on circuit 31S-FA26 (BK/RD) to the IC (Instrument Cluster). This step verifies that the IC (Instrument Cluster) input from the blower switch is OK.
- Ignition ON.
- With the engine off, place the blower motor switch in LOW.
- Enter the following diagnostic mode on the scan tool: Self-Test- IC (Instrument Cluster).
Does IC (Instrument Cluster) DTC C1779 set?
Yes
GO to G28.
No
GO to G17.
G17 CHECK THE BLOWER MOTOR SWITCH INPUT CIRCUIT FOR GROUND
- Ignition OFF.
- Disconnect: IC (Instrument Cluster) C220A.
- Ignition ON.
- Place the blower motor switch in the lowest setting.
- Measure the resistance between IC (Instrument Cluster) C220A-22, circuit 31S-FA26 (BK/RD), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to G28.
No
REPAIR circuit 31S-FA26 (BK/RD) for an open. TEST the system for normal operation.
G18 CHECK THE AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PCM PID
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button (indicator on) and monitor the ACC_CMD PCM PID.
Does the ACC_CMD PCM PID read On?
Yes
GO to G19.
No
GO to G29.
G19 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY SWITCH CONTACTS
- Ignition OFF.
- Disconnect: A/C Control Relay.
- Measure the voltage between A/C control relay socket pin, circuit 15-FA80 (GN/BK), harness side and ground.
Is the voltage greater than 10 volts?
Yes
CARRY OUT the A/C clutch relay component test.
If the relay tests OK, GO to G20.
No
VERIFY the BJB (Battery Junction Box) fuse 24 (10A) is OK. If OK, REPAIR circuit 15-FA80 (GN/BK) for an open. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation. Electrical Diagrams
G20 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY
- Ignition ON.
- Measure the voltage between ground and the A/C clutch relay socket.
Is the voltage greater than 10 volts?
Yes
GO to G21.
No
INSTALL a new Battery Junction Box (BJB). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
G21 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-2, circuit 91S-RE8 (BK/YE), harness side.
Is any voltage present?
Yes
REPAIR circuit 91S-RE8 (BK/YE) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to G22.
G22 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and PCM C175B-2, circuit 91S-RE8 (BK/YE), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to G23.
No
REPAIR circuit 91S-RE8 (BK/YE) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
G23 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between A/C clutch relay socket, circuit 91S-RE8 (BK/YE) and PCM C175B-2, circuit 91S-RE8 (BK/YE), harness side.
Is the resistance less than 5 ohms?
Yes
GO to G24.
No
REPAIR circuit 91S-RE8 (BK/YE) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
G24 CHECK THE GROUND AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Measure the resistance between A/C compressor clutch field coil C100-2, circuit 31-FA6 (BK), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to G25.
No
REPAIR circuit 31-FA6 (BK) for an open. TEST the system for normal operation.
G25 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Connect: A/C Control Relay.
- Connect: PCM C175B.
- Start the engine.
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button (indicator on).
- Measure the voltage between A/C compressor clutch field coil C100-1, circuit 15S-FA6 (GN/YE), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to G26.
No
REPAIR circuit 15S-FA7 (GN/BU)/15S-FA6 (GN/YE) for an open. TEST the system for normal operation.
G26 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 0.6 mm (0.024 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.
G27 CHECK THE GEM (Generic Electronic Module) CONNECTION
- Clear the DTCs.
- Disconnect all the GEM (Generic Electronic Module) connectors.
- Check for:
- corrosion
- pushed-out pins
- incorrectly seated connector
- Connect and correctly seat all the GEM (Generic Electronic Module) connectors.
- Operate the system.
Does the concern return?
Yes
INSTALL a new GEM (Generic Electronic 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.
G28 CHECK THE IC (Instrument Cluster) CONNECTION
- Clear the DTCs.
- Disconnect all the IC (Instrument Cluster) connectors.
- Check for:
- corrosion
- pushed-out pins
- incorrectly seated connector
- Connect and correctly seat all the IC (Instrument Cluster) connectors.
- Operate the system.
Does the concern return?
Yes
INSTALL a new IC (Instrument 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.
G29 CHECK THE PCM CONNECTION
- Clear the DTCs.
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- pushed-out pins
- incorrectly seated connector
- Connect and correctly seat all 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.