Pinpoint Test J: The A/C Is Always On: Testing
WARNING: This page is about a different car, the 2005 Mercury Montego, 2005 Ford Freestyle, and 2005 Ford Five Hundred. 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 or instrument cluster DTCs.
NOTE:
When disconnecting and reconnecting the pressure transducer electrical connector, make sure that the connetor-locking device is in place and that the locking device and connector are correctly and fully seated.
- J1 CHECK THE A/C PRESSURE PCM PID
- Key in ON position.
- Enter the following diagnostic mode on the scan tool: A/C Pressure PCM PID.
- With the manifold gauge set connected, compare the pressure readings of the manifold gauge set and the A/C pressure PID.
- Are the pressure values of the manifold gauge set and the A/C pressure PID similar?
- Yes : GO to J2.
- No : INSTALL a new A/C pressure transducer. TEST the system for normal operation.
- J2 CHECK THE A/C EVAPORATOR TEMPERATURE PID
- Allow the vehicle exterior and interior to stabilize to an ambient temperature above 16°C (60°F).
- Enter the following diagnostic mode on the scan tool: A/C Evaporator Discharge Temperature PCM PID.
- Does the A/C evaporator discharge temperature PID read similar to the ambient temperature?
- Yes : GO to J3.
- No : INSTALL a new A/C evaporator discharge temperature sensor. TEST the system for normal operation.
- J3 CHECK A/C REQUEST PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: PCM A/C REQUEST PID.
- Does the PCM A/C REQUEST PID read ON?
- J4 CHECK A/C SWITCH PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: PCM A/C SWITCH PID.
- Does the PCM A/C SWITCH PID read ON?
- Yes : INSTALL a new EATC module. TEST the system for normal operation.
- No : INSTALL a new PCM. TEST the system for normal operation.
- J5 CHECK EMTC A/C REQUEST OUTPUT
- Key in OFF position.
- Disconnect: IC C220.
- Key in ON position.
- Select the OFF position on the EMTC module.
- Measure the resistance between IC C220-10, circuit 1424 (TN/BK) and ground.
- Is the resistance less than 5 ohms?
- Yes : GO to J6.
- No : INSTALL a new PCM. TEST the system for normal operation.
- J6 CHECK CIRCUIT 1424 (TN/BK) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: EMTC C294a.
- Key in ON position.
- Measure the resistance between IC C220-10, circuit 1424 (TN/BK) and ground.
- Is the resistance greater than 10,000 ohms?
- Yes : INSTALL a new EMTC module. TEST the system for normal operation.
- No : REPAIR circuit 1424 (TN/BK) for a short to ground. TEST the system for normal operation.
- J7 CHECK A/C CLUTCH RELAY PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: PCM A/C CLUTCH RELAY PID.
- Does the PCM A/C CLUTCH RELAY PID read ON?
- Yes : REFER to INTRODUCTION - GASOLINE article .
- No : GO to J8.
- J8 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.
- Select the OFF position on the EMTC module.
- Measure the voltage between the A/C compressor clutch field coil C100-1, circuit 1810 (LG/OG) and ground.
- Is the voltage greater than 10 volts?
- Yes : GO to J9.
- No : ADJUST the A/C compressor clutch gap. REFER to AIR CONDITIONING (A/C) CLUTCH AIR GAP ADJUSTMENT . TEST the system for normal operation.
- J9 CHECK CIRCUIT 1810 (LG/OG) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: A/C Clutch Relay.
- Key in ON position.
- Measure the voltage between the A/C compressor clutch field coil C100-1, circuit 1810 (LG/OG) and ground.
- Is the voltage greater than 10 volts?
- Yes : REPAIR circuit 1810 (LG/OG) for a short to voltage. TEST the system for normal operation.
- No : INSTALL a new A/C clutch relay. Check the A/C clutch diode. INSTALL a new diode if necessary. TEST the system for normal operation.