Pinpoint Test G: The Air Conditioning (A/C) Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test G: 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 A/C is grounded. When the A/C switch is pressed, a ground is provided to the Instrument Cluster (IC) A/C switch input. When the IC 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 receives the A/C request message from the IC, it provides a ground for the A/C switch indicator. Voltage is provided to the indicator. When the GEM provides ground the indicator illuminates.
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 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 GEM does not detect excessively low refrigerant pressure from the low charge protection switch.
The A/C pressure transducer is used for A/C compressor cycling. The A/C pressure transducer is used by the PCM to turn off the A/C compressor before the refrigerant pressure is either too high or low enough to make the evaporator temperatures cold enough to freeze the condensation.
- DTC B1858 (Climate Control A/C Pressure Switch Circuit Failure) - The DTC sets when the GEM detects the an low charge protection switch or circuit when the A/C is commanded on during an on-demand self-test.
- DTC B294A (Air Conditioning Switch Short to Battery) - The DTC sets when the GEM detects excessive current draw when the GEM applies ground to the A/C switch indicator circuit, indicating a direct short to ground on the circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- A/C switch
- A/C pressure transducer
- Low charge protection switch
- A/C compressor clutch field coil
- A/C control relay
- A/C clutch air gap
- GEM
- IC
PINPOINT TEST G: THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTE: Before carrying out the following test, diagnose any PCM, GEM 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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G1 CHECK A/C PRESSURE SWITCH (AC_LOW_PRESS) GEM PID
- Start the engine.
- Enter the following diagnostic mode on the scan tool: AC_LOW_PRESS Generic Electronic Module (GEM) PID .
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button.
- Does the AC_LOW_PRESS GEM PID read ON?
Yes
GO to G5.
No
GO to G2.
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G2 CHECK A/C PRESSURE SWITCH (AC_LOW_PRESS) GEM PID WITH THE LOW CHARGE PROTECTION SWITCH BYPASSED
- Ignition OFF.
- Disconnect: Low Charge Protection Switch C1081.
- Connect a fused jumper between low charge protection switch C1081-1, circuit 7-FA11 (YE), harness side and low charge protection switch C1081-4, circuit 91-FA11 (BK/YE), harness side.
- Start the engine.
- Enter the following diagnostic mode on the scan tool: AC_LOW_PRESS GEM PID .
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button.
- Does the AC_LOW_PRESS GEM PID read ON?
Yes
INSTALL a new low charge protection switch. TEST the system for normal operation.
No
GO to G3.
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G3 CHECK THE LOW CHARGE PROTECTION SWITCH GROUND
- Ignition OFF.
- Measure the resistance between ground and low charge protection switch C1081-4., circuit 91-FA11 (BK/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G4.
No
REPAIR circuit 91-FA11 (BK/YE) for an open. TEST the system for normal operation.
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G4 CHECK CIRCUIT 7-FA11 (YE) FOR AN OPEN
- Disconnect: GEM C201E .
- Measure the resistance between function low charge protection switch C1081-1, circuit 7-FA11 (YE), harness side and GEM C201E-23, circuit 7-FA11 (YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G18.
No
REPAIR circuit 7-FA11 (YE) for an open. TEST the system for normal operation.
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G5 CHECK A/C INDICATOR OPERATION
- Start the engine.
- With the engine running, place the function selector switch to the PANEL position.
- Place the blower motor switch in the lowest position.
- Does the A/C indicator illuminate?
Yes
GO to G13.
No
GO to G6.
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G6 CHECK AC_SW IC PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: AC_SW Instrument Cluster (IC) PID .
- With the engine running, place the function selector switch in the PANEL position and press the A/C request button.
- Does the AC_SW IC PID read YES?
Yes
GO to G10.
No
GO to G7.
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G7 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 G8.
No
REPAIR circuit 91-FA13 (BK/OG) for an open. TEST the system for normal operation.
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G8 CHECK AC_SW IC PID WITH THE A/C ON
- Start the engine.
- Enter the following diagnostic mode on the scan tool: AC_SW IC PID .
- 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.
- Does the AC_SW IC PID read YES?
Yes
INSTALL a new A/C switch. TEST the system for normal operation.
No
GO to G9.
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G9 CHECK CIRCUIT 15S-FA13 (GN/RD) FOR AN OPEN
- Ignition OFF.
- Disconnect: IC C220A .
- Measure the resistance between function A/C switch C2891-6, circuit 15S-FA13 (GN/RD), harness side and IC C220A-23, circuit 15S-FA13 (GN/RD), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G19.
No
REPAIR circuit 15S-FA13 (GN/RD) for an open. TEST the system for normal operation.
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G10 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-DA6 (GN/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to G11.
No
VERIFY the CJB fuse 179 (7.5A) is OK. If OK, REPAIR circuit 15-DA6 (GN/WH) for an open. TEST the system for normal operation.
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G11 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. 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-DA6 (GN/WH), 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. TEST the system for normal operation.
No
GO to G12.
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G12 CHECK CIRCUIT 91S-FA9 (BK/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: GEM C201C .
- Measure the resistance between A/C switch C2891-5, circuit 91S-FA9 (BK/GN), harness side and GEM C201C-19, circuit 91S-FA9 (BK/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G18.
No
REPAIR circuit 91S-FA9 (BK/GN) for an open. TEST the system for normal operation.
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G13 CHECK THE A/C PRESSURE SENSOR (ACP_PRESS) PCM PID
- 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 G14.
No
INSTALL a new A/C pressure transducer. TEST the system for normal operation.
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G14 CHECK THE GROUND AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- 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 G15.
No
REPAIR circuit 31-FA6 (BK) for an open. TEST the system for normal operation.
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G15 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition 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 G16.
No
CARRY OUT the A/C clutch relay component test. If the relay tests OK, GO to G17.
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G16 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 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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G17 CHECK CIRCUIT 15-FA80 (GN/BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: A/C Control Relay .
- Measure the voltage between A/C control relay socket pin 3, circuit 15-FA80 (GN/BK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit 15-FA7 (GN/BU) for an open. TEST the system for normal operation.
No
VERIFY the Battery Junction Box (BJB) fuse 24 (10A) is OK. If OK, REPAIR circuit 15-FA80 (GN/BK) for an open. TEST the system for normal operation.
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G18 CHECK THE GEM CONNECTION
- Clear the DTCs.
- Disconnect all the GEM connectors.
- Check for:
- corrosion.
- pushed-out pins.
- incorrectly seated connector.
- Connect and correctly seat all the GEM connectors.
- Operate the system.
- Does the concern return?
Yes
INSTALL a new GEM. REFER to Body Control Systems. 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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G19 CHECK THE IC CONNECTION
- Clear the DTCs.
- Disconnect all the IC connectors.
- Check for:
- corrosion.
- pushed-out pins.
- incorrectly seated connector.
- Connect and correctly seat all the IC connectors.
- Operate the system.
- Does the concern return?
Yes
INSTALL a new IC. REFER to Instrument Panel, Gauges and Warning Indicators. 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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