Pinpoint Test F: The Air Conditioning (A/C) Is Always On
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
- F1 USE THE RECORDED DTCs FROM THE PCM SELF-TEST
- Using the recorded results from the PCM self-test:
- Is DTC P0645, P1459 or P1464 retrieved?
Yes: REFER to INTRODUCTION -- HYBRID ESCAPE & HYBRID MARINER article to continue diagnosis.
No: GO to F2.
- F2 CHECK THE FUNCTION SELECTOR SWITCH
- Key in OFF position.
- Disconnect: Function Selector Switch C294a.
- Carry out the function selector switch component test. Refer to the COMPONENT TESTS .
- Is the function selector OK?
Yes: GO to F3.
No: INSTALL a new function selector. REFER to REMOVAL AND INSTALLATION . TEST the system for normal operation.
- F3 CHECK FOR A FALSE INPUT SIGNAL TO THE PCM
- Disconnect: PCM C175b.
- Key in ON position.
- Measure the voltage between PCM and ground as follows:PINOUT REFERENCE TABLE
PCM Connector-Pin Circuit C175b-2 3053 (YE/LG) C175b-3 1398 (PK/WH) C175b-15 348 (VT) - Is any voltage present?
Yes: REPAIR the circuit(s) in question. TEST the system for normal operation.
No: GO to F4.
- F4 CHECK FOR A SHORTED A/C CLUTCH RELAY
- Key in OFF position.
- Connect: PCM C175b.
- Connect: Function Selector Switch C294a.
- Disconnect: A/C Clutch Relay C1008.
- Start the vehicle and observe the A/C compressor.
- Is the A/C compressor operating?
Yes: GO to F5.
No: INSTALL a new A/C clutch relay. TEST the system for normal operation.
- F5 CHECK CIRCUIT 321 (GY/WH) FOR A SHORT TO VOLTAGE
- Measure the voltage between A/C clutch relay C1008-5, circuit 321 (GY/WH), harness side and ground.
- Is any voltage present?
Yes: REPAIR the circuit. TEST the system for normal operation.
No: CHECK the clutch air gap. REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS .