Pinpoint Test M: The A/C Is Always On

WARNING: This page is about a different car, the 2004 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

M1 CARRY OUT THE PCM AND DATC MODULE SELF-TESTS
- Enter the following diagnostic mode on the diagnostic tool: PCM Self Test.
- Key in ON position.
- Carry out the PCM self-test. Record any DTCs.
- Carry out the DATC module self-test and retrieve continuous DTCs. Refer to CLIMATE CONTROL SYSTEM under Diagnosis and Testing. Record the DTCs displayed, if any.
- Are any PCM or DATC DTCs displayed?
  1. Yes : REFER to POWERTRAIN CONTROL MODULE (PCM) DIAGNOSTIC TROUBLE CODE (DTC) INDEX or DUAL ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (DATC) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX . CARRY OUT the necessary diagnosis and REPAIR as necessary.
  2. No : GO to M2.
M2 CHECK DATC BUTTONS
- With the engine running, toggle between DATC OFF button and the A/C button.
- DOES the A/C indicator light turn on when the A/C button is pushed, and off when the OFF button is pushed?
  1. Yes : GO to M3.
  2. No : INSTALL a new DATC module. TEST the system for normal operation.
M3 CHECK PCM PID ACCS
- Enter the following diagnostic mode on the diagnostic tool: PCM PID ACCS.
- Key in ON position.
- Push the DATC OFF button, then push the A/C button.
- Does the A/C indicator light turn off and on and the PCM PID ACCS continue to read ON?
  1. Yes : RERUN the Data Link Diagnostic Test.
  2. No : GO to M4.
M4 CHECK PID WACF WITH THE A/C OFF
- Key in ON position.
- Push the DATC OFF button.
- Enter the following diagnostic mode on the diagnostic tool: PCM PID WACF.
- Does PCM PID WACF read YES?
  1. Yes : REPAIR circuit 91S-FA79 (BK/OG) for a short to ground. TEST the system for normal operation.
  2. No : GO to M5.
M5 CHECK FOR POWER ALWAYS ON CIRCUIT 15S-FA6 (GN/YE)
- Key in OFF position.
- Disconnect: A/C Clutch C100.
- Key in ON position.
- Make sure the DATC is in the OFF position.
- Measure the voltage between A/C clutch field coil C100-2, circuit 15S-FA6 (GN/YE), harness side and ground.
  
  Fig 1: Measuring Voltage Between A/C Clutch Field Coil C100-2, Circuit 15S-FA6 (GN/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
  1. Yes : GO to M7.
  2. No : GO to M6.
M6 CHECK THE CLUTCH AIR GAP
- Measure the A/C compressor clutch air gap at three equally spaced locations between the clutch hub and the A/C compressor clutch pulley.
- Is the A/C compressor clutch air gap greater than 0.75 mm (0.030 in)?
  1. Yes : ADJUST the A/C compressor clutch field coil. TEST the system for normal operation.
  2. No : INSTALL a new A/C compressor clutch field coil. TEST the system for normal operation.
M7 CHECK CIRCUIT 15-FA6 (GN/YE) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: A/C Clutch Relay.
- Key in ON position.
- With the engine running, measure the voltage between A/C clutch field coil C100-2, circuit 15S-FA6 (GN/YE), harness side and ground.
  
  Fig 2: Measuring Voltage Between A/C Clutch Field Coil C100-2, Circuit 15S-FA6 (GN/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
  1. Yes : REPAIR circuit 15S-FA6 (GN/YE) for a short to voltage. TEST the system for normal operation.
  2. No : INSTALL a new A/C clutch relay. TEST the system for normal operation.