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Pinpoint Test O : The Air Conditioning (A/C) Is Inoperative

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

  1. O1 CHECK THE A/C SYSTEM PRESSURE

    • Ignition OFF.
    • With the R-134a manifold gauge set connected, check the A/C system pressure.

    Is the A/C system pressure above 290 kPa (42 psi) ? 

    Yes  GO to  O2.
    No  CHECK the A/C system for leaks. REFER to Fluorescent Dye Leak Detection  or Electronic Leak Detection . RECHARGE the A/C system. REFER to Air Conditioning (A/C) System Recovery, Evacuation and Charging . TEST the system for normal operation.

  2. O2 CHECK THE COMMUNICATION NETWORK

    • Ignition ON.
    • Using a diagnostic scan tool, carry out the network test.

    Do the BCM and the PCM pass the network test? 

    Yes  GO to  O3.
    No  DIAGNOSE the BCM or PCM does not communicate with the diagnostic scan tool. REFER to: Module Communications Network .

  3. O3 CHECK THE PCM (A/C) PRESSURE SENSOR (ACP_PRESS) PID

    • Using a diagnostic scan tool, monitor the ACP_PRESS PCM PID.
    • With the R-134a manifold gauge set connected, compare the pressure readings of the manifold gauge set and the ACP_PRESS PID.

    Are the pressure values of the manifold gauge set and the ACP_PRESS PID within ± 15 psi (103 kPa)? 

    Yes  GO to  O4.
    No  GO to Pinpoint Test A .

  4. O4 COMPARE THE EVAPORATOR TEMPERATURE SENSOR RESISTANCE TO THE PCM AMBIENT AIR TEMPERATURE (AAT) PID

    • Ignition OFF.
    • Allow the vehicle exterior and interior to stabilize to the ambient temperature.
    • Disconnect: Evaporator temperature sensor C296.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD31385Courtesy of FORD MOTOR COMPANY

      C296-1 component side
      GFD29916Courtesy of FORD MOTOR COMPANY
      GFD31385Courtesy of FORD MOTOR COMPANY

      C296-2 component side
    • Compare the evaporator temperature sensor measured resistance with the chart below.
      Ambient Temperature Resistance (Ohms)
      -40°C (-40°F) 1, 005, 00-1, 104, 000
      -20°C (-4°F) 287, 811-307, 800
      0°C (32°F) 96, 890-101, 300
      20°C (68°F) 37, 080-38, 000
      25°C (77°F) 29, 700-30, 300
      30°C (86°F) 23, 840-24, 430
      35°C (95°F) 19, 260-19, 820
      40°C (104°F) 15, 660-16, 180
      60°C (140°F) 7, 239-7, 594
      100°C (212°F) 1, 943-2, 091
    • Ignition ON.
    • Using a diagnostic scan tool, monitor the AAT PCM PID.

    Are the temperature values similar? 

    Yes  GO to  O5.
    No  GO to Pinpoint Test G .

  5. O5 CHECK THE FCIM (A/C) SWITCH (CC_SW_AC) PID WITH THE A/C ON

    • Start the engine.
    • Using a diagnostic scan tool, monitor the FCIM CC_SW_AC PID.
    • Select PANEL and press the A/C button (indicator on) on the HVAC controls.

    Does the PID display Active when the button is pressed and the indicator is on? 

    Yes  GO to  O6.
    No  GO to  O14.

  6. O6 CHECK THE PCM AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID WITH THE A/C ON

    • Using a diagnostic scan tool, monitor the PCM AC_REQ PID.
    • Select PANEL and press the A/C button (indicator on) on the HVAC controls.

    Does the AC_REQ PID read YES when the button is pressed and the indicator is on? 

    Yes  GO to  O7.
    No  GO to  O15.

  7. O7 CHECK THE PCM AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PID WITH THE A/C COMMANDED ON

    • Using a diagnostic scan tool, activate the PCM ACC_CMD PID.

    Does the A/C compressor turn on? 

    Yes  GO to  O15.
    No  GO to  O8.

  8. O8 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY

    • Ignition OFF.
    • Disconnect: A/C Clutch Relay.
    • Ignition ON.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD31384Courtesy of FORD MOTOR COMPANY

      A/C clutch relay socket 1
      GFD29915Courtesy of FORD MOTOR COMPANY
      		 Ground
      GFD31384Courtesy of FORD MOTOR COMPANY

      A/C clutch relay socket 3
      GFD29915Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  GO to  O9.
    No  VERIFY Battery Junction Box (BJB) fuses 79 (15A) and 30 (10A) are OK. If OK, REPAIR the circuit in question. TEST the system for normal operation. If not OK, REFER to the OEM Wiring Diagrams article to identify the possible causes of the circuit short.

  9. O9 CHECK THE A/C CLUTCH RELAY CONTROL GROUND CIRCUIT FOR AN OPEN

    • Ignition OFF.
    • Disconnect: PCM C175B.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD31384Courtesy of FORD MOTOR COMPANY

      A/C clutch relay socket 2
      GFD29916Courtesy of FORD MOTOR COMPANY
      		 C175B-2

    Is the resistance less than 3 ohms? 

    Yes  GO to  O10.
    No  REPAIR the circuit.

  10. O10 BYPASS THE A/CA/C CLUTCH RELAY

    • Ignition OFF.
    • Connect a fused jumper wire:
      Positive Lead Measurement / Action Negative Lead
      GFD31384Courtesy of FORD MOTOR COMPANY

      A/C clutch relay socket 3
      GFD30873Courtesy of FORD MOTOR COMPANY
      GFD31384Courtesy of FORD MOTOR COMPANY

      A/C clutch relay socket 5
    • Start the engine.

    Does the A/C compressor clutch engage? 

    Yes  REMOVE the fused jumper wire. INSTALL a new A/C clutch relay.
    No  LEAVE the fused jumper wire installed. GO to  O11.

  11. O11 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

    • Ignition OFF.
    • Disconnect: A/C compressor clutch field coil C100.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C100-1
      GFD29915Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  REMOVE the fused jumper wire. GO to  O12.
    No  REMOVE the fused jumper wire. REPAIR the circuit.

  12. O12 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL GROUND CIRCUIT FOR AN OPEN

    • Ignition OFF.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C100-2
      GFD29916Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance less than 3 ohms? 

    Yes  GO to  O13.
    No  REPAIR the circuit.

  13. O13 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.
    1. GFD31387Courtesy of FORD MOTOR COMPANY

    Is the A/C compressor clutch air gap average greater than 0.65 mm (0.026 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. REFER to Climate Control . TEST the system for normal operation.

  14. O14 CHECK FOR CORRECT HVAC CONTROL MODULE OPERATION

    • Disconnect and inspect all HVAC control module connectors.
    • Repair:
      • corrosion (install new connector or terminals - clean module pins)
      • damaged or bent pins - install new terminals/pins
      • pushed-out pins - install new pins as necessary
    • Reconnect all HVAC control module connectors. Make sure they seat and latch correctly.
    • Operate the system and verify the concern is still present.

    Is the concern still present? 

    Yes  CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no TSB addresses this concern, INSTALL a new HVAC control module. REFER to Climate Control .
    No  The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.

  15. O15 CHECK FOR CORRECT PCM OPERATION

    • Disconnect and inspect all PCM connectors.
    • Repair:
      • corrosion (install new connector or terminals - clean module pins)
      • damaged or bent pins - install new terminals/pins
      • pushed-out pins - install new pins as necessary
    • Reconnect all PCM connectors. Make sure they seat and latch correctly.
    • Operate the system and determine if the concern is still present.

    Is the concern still present? 

    Yes  CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no TSB addresses this concern, INSTALL a new PCM. REFER to Electronic Engine Controls .
    No  The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
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