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Pinpoint Test N : The Air Conditioning (A/C) Is Always On - A/C Mode Always Commanded On

WARNING: This page is about a different car, the 2016 Lincoln MKS. However, it is still accessible from the selected car via links, so may be relevant.

  1. N1 CHECK THE A/C SWITCH STATUS (CC_SW_AC) PID WITH THE A/C OFF

    • Ignition ON.
    • Using a diagnostic scan tool, view FCIM PIDs.
    • Monitor the CC_SW_AC FCIM PID
    • Select PANEL, press and release the A/C button (indicator off) on the HVAC controls.

    Does the PID read Active when pressed and Inactive when released? 

    Yes  GO to  N2.
    No  For 8 Inch (203mm) Touch Screen, 10 Speakers, REFER to Information and Entertainment Systems - 8-Inch (203 mm) Touchscreen, 10 Speakers Symptom Chart. For THX, 8 Inch (203mm) Touch Screen, 14 Speakers, REFER to Information and Entertainment Systems - THX® 8-Inch (203 mm) Touchscreen, 16 Speakers Symptom Chart.

  2. N2 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID WITH THE A/C OFF

    • Using a diagnostic scan tool, view PCM PIDs.
    • Deactivate the A/C using the HVAC controls.
    • Monitor the AC_REQ PCM PID

    Does the PID read OFF? 

    Yes  GO to  N4.
    No  GO to  N3.

  3. N3 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID WITH HVAC MODULE DISCONNECTED

    • Ignition OFF.
    • Disconnect: HVAC Module - DATC C228A .
    • Ignition ON.
    • Using a diagnostic scan tool, view PCM PIDs.
    • Monitor the AC_REQ PCM PID

    Does the AC_REQ PCM PID read OFF? 

    Yes  GO to  N4.
    No  GO to  N5.

  4. N4 CHECK FOR CORRECT HVAC MODULE OPERATION

    • Ignition OFF.
    • Disconnect and inspect all HVAC 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 the HVAC control module 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 HVAC module. REFER to Climate Control .
    No  The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.

  5. N5 CHECK FOR CORRECT PCM OPERATION

    • Ignition OFF.
    • 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
    • Connect 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 module connections. ADDRESS the root cause of any connector or pin issues.
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