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Pinpoint Test F: The Air Conditioning (A/C) Is Inoperative/Does Not Operate Correctly




Climate Control System

Pinpoint Tests

Pinpoint Test F: The Air Conditioning (A/C) is Inoperative/Does Not Operate Correctly

Refer to Wiring Diagram Set 55 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Automatic Climate Control System for schematic and connector information. Diagrams By Number

Normal Operation

Under normal operation, voltage is supplied to the A/C low charge protection switch through circuit CBK03 (GY). When the A/C low charge protection switch is closed (ON, pressure normal), voltage is sent to the dual-function pressure switch through circuit CH422 (VT). When the dual-function pressure switch is closed (ON, pressure normal), voltage is provided to the PCM. Ignition voltage is provided to the A/C clutch relay switch through circuit SBB13 (GY/RD). When A/C is requested, a message is sent over the Medium Speed Controller Area Network (MS-CAN) bus to the PCM. When the PCM energizes the relay, ignition voltage is supplied to the A/C clutch through circuit CH401 (VT/WH). Ground is supplied for the A/C clutch through circuit GD123 (BK/GY).

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 low-charge protection switch is not open due to excessively low refrigerant pressure. Refer to Specifications.
- The dual-function pressure switch is not open due to excessively 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°C (32°F).

This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- PCM
- HVAC module
- A/C low charge protection switch
- Dual-function pressure switch
- A/C compressor clutch field coil
- A/C clutch relay
- A/C clutch air gap
- Battery Junction Box (BJB)



PINPOINT TEST F: THE AIR CONDITIONING (A/C) IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

NOTE: Some PCM or Instrument Cluster (IC) DTCs may inhibit A/C operation. If any PCM or IC DTCs are retrieved, diagnose those first.

NOTE: Before carrying out the following test, check that the A/C system pressure is above 290 kPa (42 psi).

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F1 CHECK THE AIR CONDITIONING CLUTCH ALLOWED (ACCLT_ALW) PCM PID WITH THE A/C ON


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ACCLT_ALW PCM PID.
- Press the PANEL and A/C manual override buttons (A/C indicator ON) on the HVAC module.
- Make sure the ECON button is off (indicator not illuminated).
- Does the ACCLT_ALW PCM PID read YES?

Yes
GO to F7.

No
GO to F2.

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F2 CHECK CIRCUIT CH421 (GY) FOR VOLTAGE


- Ignition OFF.
- Disconnect: PCM C175b.
- Ignition ON.
- Measure the voltage between ground and PCM C175b-35, circuit CH421 (GY), harness side.




- Is the voltage greater than 10 volts?

Yes
GO to F16.

No
GO to F3.

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F3 CHECK CIRCUIT CH422 (VT) FOR VOLTAGE


- Ignition OFF.
- Disconnect: Dual-Function Pressure Switch C1062.
- Ignition ON.
- Measure the voltage between ground and dual-function pressure switch C1062-4, circuit CH422 (VT), harness side.




- Is the voltage greater than 10 volts?

Yes
GO to F4.

No
GO to F5.

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F4 CHECK CIRCUIT CH421 (GY) FOR AN OPEN


- Ignition OFF.
- Measure the resistance between dual-function pressure switch C1062-1, circuit CH421 (GY), harness side and PCM C175b-35, circuit CH421 (GY), harness side.




- Is the resistance less than 5 ohms?

Yes
INSTALL a new dual-function pressure switch. TEST the system for normal operation.

No
REPAIR circuit CH421 (GY) for an open. TEST the system for normal operation.

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F5 CHECK CIRCUIT CBK03 (GY) FOR VOLTAGE


- Ignition OFF.
- Disconnect: A/C Low Charge Protection Switch C130.
- Ignition ON.
- Measure the voltage between ground and A/C low charge protection switch C130-4, circuit CBK03 (GY), harness side.




- Is the voltage greater than 10 volts?

Yes
GO to F6.

No
VERIFY BJB fuse 27 (10A) is OK. If OK, REPAIR circuit CBK03 (GY) for an open. TEST the system for normal operation.

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F6 CHECK THE A/C LOW CHARGE PROTECTION SWITCH


- Ignition OFF.
- Measure the resistance between the A/C low charge protection switch terminals.




- Is the resistance less than 21 ohms?

Yes
REPAIR circuit CH422 (VT) for an open. TEST the system for normal operation.

No
INSTALL a new A/C low charge protection switch. TEST the system for normal operation.

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F7 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: ACC_CMD PCM PID.
- Press the PANEL and A/C manual override buttons (A/C indicator ON) on the HVAC module.
- Does the ACC_CMD PCM PID read ON?

Yes
GO to F11.

No
GO to F8.

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F8 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C ON


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: AC_REQ PCM PID.
- Press the PANEL and A/C manual override buttons (A/C indicator ON) on the HVAC module.
- Does the AC_REQ PCM PID read ON?

Yes
GO to F16.

No
GO to F9.

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F9 CHECK THE AIR CONDITIONING SWITCH STATUS (EVAP_TEMP) HVAC PID WITH THE A/C ON


- Enter the following diagnostic mode on the scan tool: EVAP_TEMP HVAC PID.
- Allow enough time for the evaporator to stabilize to the ambient temperature.
- Is the EVAP_TEMP HVAC PID temperature similar to the ambient temperature?

Yes
GO to F10.

No
INSTALL a new evaporator discharge sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the condition returns, GO to F16.

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F10 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_AC) HVAC PID WITH THE A/C ON


- Enter the following diagnostic mode on the scan tool: CC_AC HVAC PID.
- Press the PANEL and A/C manual override buttons (A/C indicator ON) on the HVAC module.
- Does the CC_AC HVAC PID read ON?

Yes
GO to F16.

No
GO to F15.

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F11 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL


- Ignition OFF.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Ignition ON.
- Press the PANEL and A/C manual override buttons (A/C indicator ON) 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 F13.

No
CARRY OUT the A/C clutch relay component test.

If the relay tests OK, GO to F12.

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F12 CHECK THE A/C CLUTCH RELAY FOR VOLTAGE


- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between ground and the A/C clutch relay socket, circuit SBB13 (GY/RD).




- Is the voltage greater than 10 volts?

Yes
REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.

No
VERIFY BJB fuse 13 (10A) is OK. If OK, REPAIR circuit SBB13 (GY/RD) for an open. TEST the system for normal operation.

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F13 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 C100-4, circuit GD123 (BK/GY), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to F14.

No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.

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F14 CHECK THE A/C COMPRESSOR CLUTCH AIR GAP


- Measure the A/C compressor clutch air gap at 6 equally spaced locations between the clutch hub and the A/C compressor clutch pulley.




- Is the A/C compressor clutch air gap 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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F15 CHECK THE MODULE CONNECTION


- Ignition OFF.
- Disconnect all the HVAC module connectors.
- Check 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.

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F16 CHECK THE PCM MODULE CONNECTION


- Clear the DTCs.
- Disconnect all of the PCM connectors.
- Check for:
- corrosion.
- pushed-out connectors/pins.
- incorrectly seated connector.
- Connect and correctly seat all of 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.

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