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

WARNING: This page is about a different car, the 2012 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Before carrying out the following test, diagnose any HVAC or PCM DTCs.
NOTE: Before carrying out the following test, check that the A/C system pressure is above 290 kPa (42 psi). If the pressure is below 290 kPa (42 psi), refer to FLUORESCENT DYE LEAK DETECTION  .
  1. O1 CHECK THE A/C SYSTEM PRESSURE 
  2. O2 CHECK THE A/C PRESSURE SENSOR (ACP_PRESS) PCM PID 
    • Ignition ON.
    • Enter the following diagnostic mode on the scan tool: PCM DataLogger.
    • With the R-134a manifold gauge set connected, compare the pressure readings of the manifold gauge set and the ACP_PRESS PCM PID.
    • Are the pressure values of the manifold gauge set and the ACP_PRESS PID similar? 
      • Yes  : GO to O3.
      • No  : INSTALL a new A/C pressure transducer. TEST the system for normal operation.
  3. O3 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) HVAC PID 
    • Allow the vehicle exterior and interior to stabilize to the ambient temperature.
    • Enter the following diagnostic mode on the scan tool: HVAC DataLogger.
    • Monitor the EVAP_TEMP HVAC PID
    • Does the EVAP_TEMP HVAC PID read similar to the ambient temperature? 
      • Yes  : For vehicles with navigation, GO to  O5.

        For vehicles without navigation, GO to O4.

      • No  : INSTALL a new heater core and evaporator core housing. REFER to CLIMATE CONTROL . CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  4. O4 CHECK THE (A/C) SWITCH (CC_SW_AC) HVAC PID WITH THE A/C ON 
    • Enter the following diagnostic mode on the scan tool: HVAC DataLogger.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the CC_SW_AC HVAC PID.
    • Does the CC_SW_AC HVAC PID read Active? 
      • Yes  : GO to  O6.
      • No  : GO to  O17.
  5. O5 CHECK THE (A/C) SWITCH (CC_SW_AC) FCIM PID WITH THE A/C ON 
    • Enter the following diagnostic mode on the scan tool: FCIM DataLogger.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the CC_SW_AC FCIM PID.
    • Does the CC_SW_AC FCIM PID read Active? 
  6. O6 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C ON 
    • Enter the following diagnostic mode on the scan tool: PCM DataLogger.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the AC_REQ PCM PID.
    • Does the AC_REQ PCM PID read YES? 
      • Yes  : GO to O7.
      • No  : GO to  O17.
  7. O7 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: PCM DataLogger.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls and monitor the ACC_CMD PCM PID.
    • Does the ACC_CMD PCM PID read ON? 
      • Yes  : GO to O8.
      • No  : GO to  O18.
  8. O8 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY COIL 
    • Ignition OFF.
    • Disconnect: A/C Clutch Relay.
    • Ignition ON.
    • Measure the voltage between ground and the A/C clutch relay socket, circuit CBB77 (WH).
      Fig 1: Checking Voltage To A/C Clutch Relay Coil
      G07963796Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
      • Yes  : GO to O9.
      • No  : VERIFY Battery Junction Box (BJB) fuse 77 (10A) is OK. If OK, REPAIR circuit CBB77 (WH) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams information to identify the possible causes of the circuit short.
  9. O9 CHECK THE A/C CLUTCH RELAY 
    • Start the engine.
    • Select PANEL and press the A/C button (indicator on) on the HVAC controls.
    • With the engine running, connect a 12-volt test light between A/C clutch relay socket, circuit CBB77 (WH) and A/C clutch relay socket, circuit CH302 (WH/BN).
      Fig 2: Checking A/C Clutch Relay
      G07963797Courtesy of FORD MOTOR CO.
    • Does the test light illuminate? 
      • Yes  : GO to  O12.
      • No  : GO to O10.
  10. O10 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE 
    • Ignition OFF.
    • Disconnect: PCM C1381B (5.0L, 6.2L).
    • Disconnect: PCM C175B (3.7L).
    • Disconnect: PCM C1551B (3.5L).
    • Ignition ON.
    • Measure the voltage between ground and:
      • For 3.7L, PCM C175B-12, circuit CH302 (WH/BN), harness side.
      • For 5.0L and 6.2L, PCM C1381B-12, circuit CH302 (WH/BN), harness side.

      For 3.7L, 5.0L and 6.2L 

      Fig 3: Measuring Voltage Between PCM C175B-12, Circuit CH302 (WH/BN) And Ground
      G06098542Courtesy of FORD MOTOR CO.
    • For 3.5L, measure the voltage between ground and PCM C1551B-2, circuit CH302 (WH/BN), harness side.

      For 3.5L 

      Fig 4: Measuring Voltage Between PCM C1551B-2, Circuit CH302 (WH/BN) And Ground
      G07412906Courtesy of FORD MOTOR CO.
    • Is any voltage present? 
      • Yes  : REPAIR circuit CH302 (WH/BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
      • No  : GO to O11.
  11. O11 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • Measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and:
      • For 3.7L, PCM C175B-12, circuit CH302 (WH/BN), harness side.
      • For 5.0L and 6.2L, PCM C1381B-12, circuit CH302 (WH/BN), harness side.

      For 3.7L, 5.0L and 6.2L 

      Fig 5: Measuring Resistance Between A/C Clutch Relay Socket, Circuit CH302 (WH/BN) And PCM C175B-12, Circuit CH302 (WH/BN)
      G07412909Courtesy of FORD MOTOR CO.
    • For 3.5L, measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and PCM C1551B-2, circuit CH302 (WH/BN), harness side.

      For 3.5L 

      Fig 6: Measuring Resistance Between A/C Clutch Relay Socket, Circuit CH302 (WH/BN) And PCM C1551B-2, Circuit CH302 (WH/BN)
      G07412910Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
      • Yes  : GO to  O18.
      • No  : REPAIR circuit 302 (WH/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  12. O12 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY SWITCH CONTACTS 
    • Measure the voltage between the A/C clutch relay socket, circuit SBB30 (BN/RD) and ground.
      Fig 7: Measuring Voltage Between A/C Clutch Relay Socket And Ground
      G06133070Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
      • Yes  : GO to O13.
      • No  : VERIFY Battery Junction Box (BJB) fuse 30 (10A) is OK. If OK, REPAIR circuit SBB30 (BN/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams information to identify the possible causes of the circuit short.
  13. O13 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • Disconnect: A/C Compressor Clutch Field Coil C100.
    • Measure the resistance between the A/C clutch relay socket, circuit CH401 (VT/WH) and A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side.
      Fig 8: Checking A/C Compressor Clutch Field Coil Voltage Circuit For Open
      G06141382Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
      • Yes  : GO to O14.
      • No  : REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
  14. O14 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL 
    • Connect: A/C Clutch Relay.
    • Ignition ON.
    • Select PANEL and press the A/C button (indicator on) on the HVAC controls.
    • Measure the voltage between A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side and ground.
      Fig 9: Measuring Voltage Between A/C Compressor Clutch Field Coil C100-1, Circuit CH401 (VT/WH), Harness Side And Ground
      G06064573Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
      • Yes  : GO to O15.
      • No  : INSTALL a new A/C clutch relay. TEST the system for normal operation.
  15. O15 CHECK THE GROUND AT THE A/C COMPRESSOR CLUTCH FIELD COIL 
    • Ignition OFF.
    • Measure the resistance between A/C compressor clutch field coil C100-2, circuit GD123 (BK/GY), harness side and ground.
      Fig 10: Measuring Resistance Between A/C Compressor Clutch Field Coil C100-2, Circuit GD123 (BK/GY), Harness Side And Ground
      G06098588Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
      • Yes  : GO to O16.
      • No  : REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
  16. O16 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.
      Fig 11: Checking A/C Compressor Clutch Air Gap
      G06064575Courtesy of FORD MOTOR CO.
    • Is the A/C compressor clutch air gap average greater than 0.65 mm (0.026 in)? 
  17. O17 CHECK THE HVAC MODULE CONNECTION 
    • Inspect the HVAC module connectors for:
      • corrosion
      • pushed-out terminals
      • damaged terminals
    • Connect and correctly seat all the HVAC module connectors.
    • Clear the DTCs.
    • Enter the following diagnostic mode on the scan tool: Self-Test - HVAC Module.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
      • Yes  : INSTALL a new HVAC module. REFER to CLIMATE CONTROL . 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.
  18. O18 CHECK THE PCM CONNECTION 
    • Disconnect all the PCM connectors.
    • Inspect the PCM connectors for:
      • corrosion
      • pushed-out terminals
      • damaged terminals
    • Connect and correctly seat all the PCM connectors.
    • Clear the DTCs.
    • Enter the following diagnostic mode on the scan tool: Self-Test - PCM.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
      • Yes  : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS . 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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