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

WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. 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, PCM or IC DTCs first.
  1. L1 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)? 
  2. L2 CHECK THE A/C PRESSURE SENSOR (ACP_PRESS) PCM PID 
    • Ignition ON.
    • Enter the following diagnostic mode on the scan tool: ACP_PRESS PCM PID.
    • With the 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 PCM PID similar? 
    • Yes  : GO to L3.
    • No  : INSTALL a new A/C pressure transducer. TEST the system for normal operation.
  3. L3 CHECK THE A/C EVAPORATOR TEMPERATURE (EVAP_TEMP) HVAC PID 
    • Allow the vehicle exterior and interior to stabilize to the outside ambient temperature.
    • Enter the following diagnostic mode on the scan tool: EVAP_TEMP HVAC PID.
    • Does the EVAP_TEMP HVAC PID read similar to the ambient temperature? 
    • Yes  : GO to L4.
    • No  : INSTALL a new evaporator temperature sensor. REFER to CLIMATE CONTROL . TEST the system for normal operation.
  4. L4 CHECK THE A/C SWITCH (CC_SW_AC) HVAC PID WITH THE A/C ON 
    • Enter the following diagnostic mode on the scan tool: CC_SW_AC HVAC PID.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls.
    • Does the CC_SW_AC HVAC PID read ON? 
    • Yes  : GO to L5.
    • No  : GO to  L16.
  5. L5 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C ON 
    • Start the engine.
    • Enter the following diagnostic mode on the scan tool: AC_REQ PCM PID.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls.
    • Does the AC_REQ PCM PID read YES? 
    • Yes  : GO to L6.
    • No  : GO to  L16.
  6. L6 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.
    • Select PANEL press the A/C button (indicator on) on the HVAC controls.
    • Does the ACC_CMD PCM PID read ON? 
    • Yes  : GO to L7.
    • No  : GO to  L17.
  7. L7 CHECK THE VOLTAGE AT THE A/C COMPRESSOR CLUTCH FIELD COIL 
    • Ignition OFF.
    • Disconnect: A/C Compressor Clutch Field Coil C100.
    • Start the engine.
    • Select PANEL and A/C on the HVAC module.
    • Measure the voltage between A/C compressor clutch field coil C100-1, circuit CH401 (VT/WH), harness side and ground.
      Fig 1: 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? 
  8. L8 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 GD124 (BK/VT) or GD122 (BK) (diesel), harness side and ground.
      Fig 2: Measuring Resistance Between A/C Compressor Clutch Field Coil C100-2, Circuit GD124 (BK/VT) Or GD122 (BK) (Diesel) And Ground
      G06098588Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to L9.
    • No  : REPAIR circuit GD124 (BK/VT) or GD122 (BK) (diesel) for an open. TEST the system for normal operation.
  9. L9 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL 
    • Measure the resistance between the A/C compressor clutch field coil C100 terminals, component side.
    • Is the resistance 2-5 ohms? 
    • Yes  : GO to L10.
    • No  : INSTALL a new A/C compressor clutch field coil. REFER to CLIMATE CONTROL . TEST the system for normal operation.
  10. L10 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL FOR A SHORT TO GROUND 
    • Measure the resistance between the A/C compressor clutch field coil C100 terminals, component side and ground.
    • Is the resistance greater than 10, 000 ohms? 
  11. L11 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY SWITCH CONTACTS 
    • Ignition OFF.
    • Disconnect: A/C Clutch Relay.
    • Ignition ON.
    • Measure the voltage between A/C clutch relay socket, circuit SBB47 (WH/RD) and ground.
      Fig 3: Measuring Voltage Between A/C Clutch Relay Socket, Circuit SBB47 (WH/RD) And Ground
      G07973744Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes  : GO to L12.
    • No  : VERIFY Battery Junction Box (BJB) fuse 47 (10A) is OK. If OK, REPAIR circuit SBB47 (WH/RD) for an open. TEST the system for normal operation. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.
  12. L12 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY COIL 
    • Measure the voltage between A/C clutch relay socket, circuit CBB35 (YE/GY) and ground.
      Fig 4: Measuring Voltage Between A/C Clutch Relay Socket, Circuit CBB35 (YE/GY) And Ground
      G07484426Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes  : GO to L13.
    • No  : VERIFY Battery Junction Box (BJB) fuse 35 (10A) is OK. If OK, REPAIR circuit CBB35 (YE/GY) for an open. TEST the system for normal operation. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.
  13. L13 CHECK THE A/C COMPRESSOR CLUTCH FIELD COIL VOLTAGE CIRCUIT FOR AN OPEN 
    • Measure the resistance between 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 5: Measuring Resistance Between A/C Clutch Relay Socket, Circuit CH401 (VT/WH) And A/C Compressor Clutch Field Coil C100-1, Circuit CH401 (VT/WH)
      G07973746Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10, 000 ohms? 
    • Yes  : GO to L14.
    • No  : REPAIR circuit CH401 (VT/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  14. L14 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE 
    • Ignition OFF.
    • Disconnect: PCM C175B (Gasoline).
    • Disconnect: PCM C1232B (Diesel).
    • Ignition ON.
    • Measure the voltage between ground and PCM C175B-12, circuit CH302 (WH/BN), harness side.

      For gasoline engines 

      Fig 6: Measuring Voltage Between Ground And PCM C175B-12, Circuit CH302 (WH/BN), Harness Side
      G06098542Courtesy of FORD MOTOR CO.
    • Measure the voltage between ground and PCM C1232B-2, circuit CH302 (WH/BN), harness side.

      For diesel engines 

      Fig 7: Measuring Voltage Between Ground And PCM C1232B-2, Circuit CH302 (WH/BN), Harness Side
      G06133020Courtesy 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 L15.
  15. L15 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 PCM C175B-12, circuit CH302 (WH/BN), harness side.

      For gasoline engines 

      Fig 8: Measuring Resistance Between A/C Clutch Relay Socket, Circuit CH302 (WH/BN) And PCM C175B-12, Circuit CH302 (WH/BN)
      G07484427Courtesy of FORD MOTOR CO.
    • Measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and PCM C1232B-2, circuit CH302 (WH/BN), harness side.

      For diesel engines 

      Fig 9: Measuring Resistance Between A/C Clutch Relay Socket, Circuit CH302 (WH/BN) And PCM C1232B-2, Circuit CH302 (WH/BN)
      G07484428Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to  L17.
    • No  : REPAIR circuit CH302 (WH/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  16. L16 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.
    • 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  17. L17 CHECK THE PCM CONNECTION 
    • Disconnect all the PCM connectors.
    • Inspect the HVAC module connectors for:
      • corrosion.
      • pushed-out terminals.
      • damaged terminals.
    • Connect and correctly seat all the PCM connectors.
    • Clear the DTCs.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • 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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