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Pinpoint Test Aa: Insufficient Air Conditioning (A/C) Cooling

WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
  1. AA1 CHECK FOR COOLANT FLOW TO THE HEATER CORE 
    WARNING: The heater core inlet hose will become too hot to handle and may cause serious burns if the system is working correctly.
    • Run the engine until it reaches normal operation temperature.
    • Press the PANEL, RECIRC and A/C buttons on the DATC module or select MAX A/C on the function selector switch. Set the temperature control to full COOL.
    • Feel the heater core inlet hose to see if it is hot.
      Fig 1: Checking For Coolant Flow To Heater Core
      G03945028Courtesy of FORD MOTOR CO.
    • Is the heater core inlet hose hot? 
  2. AA2 CHECK FOR VACUUM AT THE HEATER CONTROL VALVE 
    • Disconnect the heater control valve vacuum connector and check for vacuum.
      Fig 2: Locating Heater Control Valve Vacuum Connector
      G03910132Courtesy of FORD MOTOR CO.
    • Is vacuum present at the heater control valve? 
    • Yes  : INSTALL a new heater control valve. REFER to HEATING AND VENTILATION . TEST the system for normal operation.
    • No  : GO to AA3.
  3. AA3 CHECK THE HEATER CONTROL VALVE VACUUM LINE FOR BLOCKAGE 
    • Key in OFF position.
      • NOTE: Manual climate control systems only.
      Fig 3: Disconnecting Function Selector Switch Vacuum Connector
      G03945141Courtesy of FORD MOTOR CO.
    • Disconnect the function selector switch vacuum connector. Connect the vacuum pump to the heater control valve vacuum line and attempt to pull a vacuum.
      • NOTE: DATC systems only.
      Fig 4: Connecting Vacuum Pump To Heater Control Valve Vacuum Line
      G03945142Courtesy of FORD MOTOR CO.
    • Disconnect the ATC solenoid and manifold vacuum connector. Connect the vacuum pump to the heater control valve vacuum line and attempt to pull a vacuum.
    • Can a vacuum be pulled on the heater control valve vacuum line? 
    • Yes  : INSTALL a new vacuum harness. TEST the system for normal operation.
    • No  : GO to AA4.
  4. AA4 CHECK THE HEATER CONTROL VALVE VACUUM LINE FOR LEAKS 
    • Plug the heater control valve vacuum line at the heater control valve connection.
      • NOTE: Manual climate control systems only.
      Fig 5: Checking Heater Control Valve Vacuum Line For Leaks
      G03945141Courtesy of FORD MOTOR CO.
    • Leak test the heater control valve vacuum line, using the vacuum pump.
      • NOTE: DATC systems only.
      Fig 6: Testing Leak Heater Control Valve Vacuum Line, Using Vacuum Pump
      G03945142Courtesy of FORD MOTOR CO.
    • Leak test the heater control valve vacuum line, using the vacuum pump.
    • Does the heater control valve vacuum line leak? 
    • Yes  : INSTALL a new vacuum harness. TEST the system for normal operation.
    • No  : GO to AA5.
  5. AA5 CHECK FOR INCORRECT VACUUM LINE PLACEMENT 
    • Key in OFF position.
    • Inspect the heater control valve and A/C vacuum lines for correct placement.
    • Is the vacuum line placement correct? 
    • Yes  : Manual climate control systems, INSTALL a new climate control assembly. CONTROL COMPONENTS . TEST the system for normal operation.

      DATC systems, GO to AA6.

    • No  : CORRECT the vacuum line placement. TEST the system for normal operation.
  6. AA6 CHECK THE ATC SOLENOID AND MANIFOLD CIRCUIT VOLTAGE 
    • Connect the vacuum harness connector to the ATC solenoid and manifold.
    • Key in ON position.
    • Press the PANEL, RECIRC and A/C buttons on the DATC module.
      • NOTE: The following measurement must be taken by back-probing the ATC solenoid and manifold C2093.
      Fig 7: Checking ATC Solenoid And Manifold Circuit Voltage
      G03945145Courtesy of FORD MOTOR CO.
    • Measure the voltage between ATC solenoid and manifold C2093-1, circuit 1070 (BN/LB) and C2093-6, circuit 1069 (OG/LB).
    • Is all the voltage greater than 10 volts? 
    • Yes  : INSTALL a new ATC solenoid and manifold. TEST the system for normal operation.
    • No  : GO to AA7.
  7. AA7 CHECK THE ATC SOLENOID AND MANIFOLD CIRCUIT 1069 (OG/LB) FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: DATC Module C228a and ATC Solenoid and Manifold C2093.
    • Measure the resistance between the DATC module C228a-14, circuit 1069 (OG/LB) and the ATC solenoid and manifold C2093-6, circuit 1069 (OG/LB).
      Fig 8: Checking ATC Solenoid And Manifold Circuit 1069 (OG/LB) For An Open
      G03945146Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : INSTALL a new DATC module. REFER to CONTROL COMPONENTS . TEST the system for normal operation.
    • No  : REPAIR the for an open. TEST the system for normal operation.
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