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

WARNING: This page is about a different car, the 2012 Ford Flex. 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.

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 .

M1 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 PID.
- Are the pressure values of the manifold gauge set and the ACP_PRESS PID similar?
  - Yes : GO to M2.
  - No : INSTALL a new A/C pressure transducer. TEST the system for normal operation.
M2 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 M3.
  - No : INSTALL a new A/C evaporator discharge temperature sensor. TEST the system for normal operation.
M3 CHECK THE (A/C) SWITCH (CC_SW_AC) FCIM PID WITH THE A/C ON
NOTE: Before carrying out this test step, be sure all other FCIM button functions are operational. If all other buttons operate correctly, continue with this test step. If multiple buttons are inoperative and DTC U0256:00 is not present, install a new FCIM. Test the system for normal operation. If DTC U0256:00 is present, diagnose the DTC first.
- Enter the following diagnostic mode on the scan tool: CC_SW_AC FCIM PID.
- Select PANEL press the A/C button (indicator on) on the HVAC controls.
- Does the CC_SW_AC FCIM PID read Active?
  - Yes : For 3.5L only , GO to M4.
    For 3.5L Gasoline Turbocharged Direct Injection (GTDI) only , GO to M5.
  - No : INSTALL a new FCIM. TEST the system for normal operation.
M4 CHECK THE AIR CONDITIONING COMPRESSOR CYCLING SWITCH (ACCS) PCM PID WITH THE A/C ON
- Start the engine.
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Select PANEL press the A/C button (indicator on) on the HVAC controls.
- Does the ACCS PCM PID read ON?
  - Yes : For vehicles equipped with navigation, GO to M6.
    For vehicles not equipped with navigation, GO to M7.
  - No : GO to M14.
M5 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 ON?
  - Yes : For all vehicles equipped with navigation, GO to M6.
    For 3.5L only vehicles not equipped with navigation, GO to M7.
    
    For 3.5L GTDI only vehicles not equipped with navigation, GO to M8.
  - No : GO to M14.
M6 CHECK THE MAX A/C OPERATION
NOTE: Before carrying out this test step, be sure all other ACM touch screen functions are operational. If all other touch screen functions operate correctly, continue with this test step. If multiple touch screen functions are inoperative and DTC U0163:00 is not present, install a new ACM. Test the system for normal operation. If DTC U0163:00 is present, diagnose the DTC first.
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Select MAX A/C on the navigation screen.
- Does the ACCS PCM PID read ON?
  - Yes : For 3.5L only , GO to M7.
    For 3.5L GTDI only , GO to M8.
  - No : INSTALL a new ACM. TEST the system for normal operation.
M7 CHECK THE AIR CONDITIONING CLUTCH (WAC/ACCR) PCM PID WITH THE A/C ON
- Enter the following diagnostic mode on the scan tool: WAC/ACCR PCM PID.
- Select PANEL press the A/C button (indicator on) on the HVAC controls.
- Does the WAC/ACCR PCM PID read ON?
  - Yes : GO to M9.
  - No : GO to M15.
M8 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 M9.
  - No : GO to M15.
M9 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)
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
  - Yes : GO to M10.
  - No : GO to M13.
M10 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 GD120 (BK/GN), harness side and ground.
  
  Fig 2: Measuring Resistance Between A/C Compressor Clutch Field Coil C100-2, Circuit GD120 (BK/GN) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
  - Yes : GO to M11.
  - No : REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
M11 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 M12.
  - No : INSTALL a new A/C compressor clutch field coil. TEST the system for normal operation.
M12 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?
  - 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. TEST the system for normal operation.
M13 CHECK THE A/C CLUTCH RELAY FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between A/C clutch relay socket, circuit SBB24 (VT/RD) and ground.
  
  Fig 3: Measuring Voltage Between A/C Clutch Relay Socket, Circuit SBB24 (VT/RD) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
  - Yes : CARRY OUT the A/C clutch relay component test.
    Refer to COMPONENT TESTING for component testing. If the relay tests OK, REPAIR circuit CH401 (VT/WH) for an open. TEST the system for normal operation.
  - No : VERIFY Battery Junction Box (BJB) fuse 24 (10A) is OK. If OK, REPAIR circuit SBB24 (VT/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams manual to identify the possible causes of the circuit short.
M14 CHECK THE MODULE CONNECTION
- Inspect the 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. If the condition returns, GO to M13.
  - No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
M15 CHECK THE PCM CONNECTION
- Disconnect all the PCM connectors.
- Inspect the 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.