Pinpoint Test F: The Air Conditioning (A/C) Is Always On - A/C Compressor Does Not Cycle
Climate Control System
Pinpoint Tests
Pinpoint Test F: The Air Conditioning (A/C) Is Always On - A/C Compressor Does Not Cycle
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
NOTE: Before carrying out the following test, diagnose any PCM DTCs.
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:
- Wiring, terminals or connectors
- PCM
- Function selector switch
- A/C control relay
- A/C clutch air gap
PINPOINT TEST F: THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C COMPRESSOR DOES NOT CYCLE
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F1 CHECK THE AIR CONDITIONING CYCLING SWITCH (ACCS) PCM PID WITH THE A/C OFF
- Ignition ON.
- Turn the function selector switch to the OFF position.
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Does the ACCS PCM PID read OFF?
Yes
GO to F2.
No
GO to F3.
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F2 CHECK THE AIR CONDITIONING CLUTCH (WAC/ACCR) PCM PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: WAC/ACCR PCM PID.
- Does the WAC/ACCR PCM PID read OFF?
Yes
CARRY OUT the A/C clutch relay component test.
If the relay tests OK, GO to F5.
No
GO to F7.
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F3 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 any voltage present?
Yes
GO to F4.
No
GO to F7.
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F4 CHECK THE A/C CYCLING SWITCH
- Ignition OFF.
- Disconnect: A/C Cycling Switch C130.
- Remove the A/C cycling switch from the vehicle.
- Measure the resistance between the A/C cycling switch terminals.
- Is the resistance greater than 10,000 ohms?
Yes
REPAIR circuit CH425 (GN/BU) for an open. TEST the system for normal operation.
No
INSTALL a new A/C cycling switch. TEST the system for normal operation.
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F5 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL AIR GAP
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Ignition ON.
- Measure the voltage between ground and A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side.
- Is any voltage present?
Yes
REPAIR circuit CH401 (VT/WH) for a short to voltage. TEST the system for normal operation.
No
GO to F6.
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F6 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 0.75 mm (0.030 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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F7 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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