Pinpoint Test D: The Air Conditioning (A/C) Is Always On

WARNING: This page is about a different car, the 2005 Ford RV Cutaway, 2005 Ford Econoline, 2005 Ford E450 Super Duty, and 2005 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Before carrying out the following test, diagnose any PCM DTCs.

D1 CHECK PID WACF WITH THE A/C OFF
- Key in ON position.
- Place the function selector switch to the OFF position.
- Enter the following diagnostic mode on the diagnostic tool: PCM PID WACF.
- Does the PCM PID WACF read YES?
- Yes : REPAIR circuit 331 (PK/YE) for a short to ground. TEST the system for normal operation.
- No : GO to D2.
D2 CHECK PID ACCS WITH THE A/C OFF
- Enter the following diagnostic mode on the diagnostic tool: PCM PID ACCS.
- Does the PCM PID ACCS read ON?
- Yes : GO to D3.
- No : GO to D7.
D3 CHECK FOR VOLTAGE AT THE A/C CYCLING SWITCH
- Key in OFF position.
- Disconnect: A/C Cycling Switch C1081.
- Key in ON position.
- Measure the voltage between A/C cycling switch C130-1, circuit 348 (VT) and ground.
  
  Fig 1: Measuring Voltage Between A/C Cycling Switch And Ground
  Courtesy of FORD MOTOR CO.
- Is voltage present?
- Yes : GO to D4.
- No : GO to D5.
D4 CHECK CIRCUIT 348 (VT) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: Function Selector Switch C294a.
- Key in ON position.
- Measure the voltage between A/C cycling switch C130-1, circuit 348 (VT) and ground.
  
  Fig 2: Measuring Voltage Between A/C Cycling Switch And Ground
  Courtesy of FORD MOTOR CO.
- Is voltage present?
- Yes : REPAIR circuit 348 (VT) for a short to voltage. TEST the system for normal operation.
- No : INSTALL a new function selector switch. TEST the system for normal operation.
D5 CHECK CIRCUIT 441 (RD/YE) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: Dual Function Pressure Switch C1062.
- Key in ON position.
- Measure the voltage between dual function pressure switch C1062-1, circuit 441 (RD/YE) and ground.
- Measure the voltage between A/C high pressure switch C1078-3, circuit 441 (RD/YE) and ground.
- Is voltage present?
- Yes : REPAIR circuit 441 (RD/YE) for a short to voltage. TEST the system for normal operation.
- No : GO to D6.
D6 CHECK CIRCUIT 347 (BK/YE) FOR A SHORT TO VOLTAGE
- Measure the voltage between dual function pressure switch C1062-4, circuit 347 (BK/YE) and ground.
- Measure the voltage between dual function pressure switch C1078-1, circuit 347 (BK/YE) and ground.
- Is voltage present?
- Yes : REPAIR circuit 347 (BK/YE) for a short to voltage. TEST the system for normal operation.
- No : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS - GASOLINE ENGINES . TEST the system for normal operation.
D7 CHECK FOR VOLTAGE TO THE A/C COMPRESSOR CLUTCH FIELD COIL
- Key in OFF position.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Key in ON position.
- Measure the voltage between A/C compressor clutch field coil C100-2, circuit 321 (GY/WH) and ground.
  
  Fig 7: Measuring Voltage Between A/C Compressor Clutch Field Coil Circuit 321 And Ground
  Courtesy of FORD MOTOR CO.
- Is voltage present?
- Yes : GO to D8.
- No : ADJUST the A/C compressor clutch air gap. REFER to AIR CONDITIONING (A/C) CLUTCH AIR GAP ADJUSTMENT . TEST the system for normal operation.
D8 CHECK CIRCUIT 321 (GY/WH) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: A/C Control Relay.
- Key in ON position.
- Measure the voltage between A/C compressor clutch field coil C100-2, circuit 321 (GY/WH) and ground.
  
  Fig 8: Measuring Voltage Between A/C Compressor Clutch Field Coil Circuit 321 And Ground
  Courtesy of FORD MOTOR CO.
- Is voltage present?
- Yes : REPAIR circuit 321 (GY/WH) for a short to voltage. TEST the system for normal operation.
- No : INSTALL a new A/C control relay. TEST the system for normal operation.