Pinpoint Test E: The Air Conditioning (A/C) is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test E: 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, the function selector switch is supplied voltage. When any mode requiring A/C is selected, the function selector switch sends voltage to the A/C high-pressure switch. Voltage is then supplied from the A/C high-pressure switch to the A/C cycling switch. The voltage is then supplied from the A/C cycling switch to the PCM.
Voltage is supplied to the A/C clutch relay switch contact. When the relay is energized, voltage is sent to the A/C compressor clutch field coil. The A/C compressor clutch field coil is grounded.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- PCM
- Function selector switch
- A/C cycling switch
- A/C high-pressure switch
- A/C compressor clutch field coil
- A/C control relay
- A/C clutch air gap
PINPOINT TEST E: THE AIR CONDITIONING (A/C) IS INOPERATIVE
NOTE: Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retrieved, diagnose those first. Refer to Computers and Control Systems Information.
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.
NOTE: The ambient temperature must be over 6°C (43°F).
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E1 CHECK THE AIR CONDITIONING CYCLING SWITCH (ACCS) PCM PID
- Ignition ON.
- With the engine running, turn the function selector switch to the MAX A/C position.
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Does the ACCS PCM PID read ON?
Yes
GO to E2.
No
GO to E7.
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E2 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 E3.
No
GO to E14.
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E3 CHECK CIRCUIT SBB25 (RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
For 2.3L only
- For 2.3L only, measure the voltage between ground and A/C clutch relay socket pin 3, circuit SBB25 (RD).
For 3.0L and 4.0L only
- For 3.0L and 4.0L only, measure the voltage between ground and A/C clutch relay socket pin 3, circuit SBB25 (RD).
- Is the voltage greater than 10 volts?
Yes
CARRY OUT the A/C Clutch Relay Component Test.
If the relay tests OK, GO to E4.
No
VERIFY Battery Junction Box (BJB) fuse 25 (10A) is OK. If OK, REPAIR circuit SBB25 (RD) for an open. TEST the system for normal operation.
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E4 CHECK CIRCUIT CH401 (VT/WH) FOR AN OPEN
- Ignition OFF.
- Disconnect: A/C Clutch C100.
For 2.3L only
- For 2.3L only, measure the resistance between A/C clutch relay socket pin 5, circuit CH401 (VT/WH) and A/C clutch C100-1, circuit CH401 (VT/WH), harness side.
For 3.0L and 4.0L only
- For 3.0L and 4.0L only, measure the resistance between A/C clutch relay socket pin 5, circuit CH401 (VT/WH) and A/C clutch C100-1, circuit CH401 (VT/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E5.
No
REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
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E5 CHECK FOR GROUND AT THE A/C COMPRESSOR CLUTCH FIELD COIL
- Measure the resistance between ground and A/C clutch C100-2, circuit GD121 (BK/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E6.
No
REPAIR circuit GD121 (BK/YE) for an open. TEST the system for normal operation.
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E6 CHECK THE A/C COMPRESSOR CLUTCH AIR GAP
- Ignition OFF.
- 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 compressor clutch air gap greater than 0.75 mm (0.030 in)?
Yes
ADJUST the A/C compressor clutch air 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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E7 CHECK CIRCUIT CH425 (GN/BU) FOR VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175b.
- Ignition ON.
- Measure the voltage between ground and PCM C175b-15, circuit CH425 (GN/BU), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to E14.
No
GO to E8.
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E8 CHECK CIRCUIT CH423 (YE) FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Cycling Switch C1081.
- Ignition ON.
- Measure the voltage between ground and A/C cycling switch C1081-1, circuit CH423 (YE), harness side.
- Is the voltage greater then 10 volts?
Yes
GO to E9.
No
GO to E10.
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E9 CHECK CIRCUIT CH425 (GN/BU) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between A/C cycling switch C1081-4, circuit CH425 (GN/BU), harness side and PCM C175b-15, circuit CH425 (GN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new A/C cycling switch. TEST the system for normal operation.
No
REPAIR circuit CH425 (GN/BU) for an open. TEST the system for normal operation.
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E10 CHECK CIRCUIT CH443 (GN/OG) FOR VOLTAGE
- Disconnect: A/C High-Pressure Switch C1078.
- Ignition ON.
- Measure the voltage between ground and A/C high-pressure switch C1078-1, circuit CH443 (GN/OG), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to E11.
No
GO to E12.
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E11 CHECK CIRCUIT CH423 (YE) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between A/C cycling switch C1081-1, circuit CH423 (YE), harness side and A/C high-pressure switch C1078-3, circuit CH423 (YE), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new A/C high-pressure switch. TEST the system for normal operation.
No
REPAIR circuit CH423 (YE) for an open. TEST the system for normal operation.
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E12 CHECK CIRCUIT CBP27 (GN/BN) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Function Selector Switch C294a.
- Ignition ON.
- Measure the voltage between ground and function selector switch C294a-1, circuit CBP27 (GN/BN), harness side.
- Is the voltage greater than 10 volts?
Yes
GO to E13.
No
VERIFY Smart Junction Box (SJB) fuse 27 (10A) is OK. If OK, REPAIR circuit CBP27 (GN/BN). TEST the system for normal operation.
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E13 CHECK CIRCUIT CH443 (GN/OG) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between function selector switch C294a-2, circuit CH443 (GN/OG), harness side and A/C high-pressure switch C1078-1, circuit CH443 (GN/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new function selector switch. TEST the system for normal operation.
No
REPAIR circuit CH443 (GN/OG) for an open. TEST the system for normal operation.
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E14 CHECK MODULE CONNECTIONS
- Disconnect all PCM connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all PCM connectors 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. Concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
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