What is causing my radiator fan to constantly run on my 2000 Mercury Villager?

I bought this van used. The radiator fan constantly runs as soon as the engine is started. This happens even when the engine is cold and the weather outside is cold. The fan then turns off when the engine is shut off.

What could be the cause and how do I troubleshoot this?

Things I have already done:

1. Thermostat has been replaced.

2. Engine Coolant Temperature Sensor has been replaced.

3. Three fan related relays have been tested and presumed to be in good working order.

After researching online, one person has found that replacing the ECM under the glovebox has fixed the problem.

Does anyone have any further DIY suggestions? Thank you to anyone who can provide insight!

3 Answers

  • 6 years ago
    Favorite Answer

    Have you tested the Temperature Sending Unit?

    How did you test the relays, with a voltmeter? Did you hear a clicking noise when you put power through it? If not, the relay is stuck in the closed position and that is why it is always running.

    Source(s): 30 yrs home mech and Mech Eng
  • rich
    Lv 6
    6 years ago

    some cars have fan that run as soon as the car starts to cool the radiator and engine the fluid in the rad. is 190 degrees or more the engine runs at that temp the manifolds at the sides of the engine run at 400 degrees making the engine very hot winter or not had the opposite not working should be better that it does work and all the time does not mean it is broke good luck

  • 6 years ago

    COOLING FAN SWITCH is different from ENGEIN TEMP SWITCH! the TEMP switch goes to the COMPUTER and the FAN SWITCH turns the FAN off and on. USE ONLY FACTORY COOLANTS and ask at DEALERSHIP Because there migh hav been a RECALL on this issues! GOOD LUCK!!

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