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  • Mike Gerber ·
    Hi Nic,

    The cooling fan switch is a separate switch screwed in to the bottom of the radiator with 2 wires leading to it. When it senses a certain temperature it closes and turns on the fans. As the coolant cools down, it opens, turning off the fans. A relay is a device that handles bigger electrical loads. The ECT sensor is what feeds engine temperature to the ECU. I don't believe that is your problem. This assumes that your Corolla is set up like the Camry. Both these items can be tested. You will need a manual and a cheap digital volt/ohmmeter. If you don't have one, a simple test of the relay is to locate it in a relay box or fuse box. Then see of there is another identical relay from a non critical area of the car inside that box, and substitute it for the cooling fan relay. If the problem goes away, you have found the culprit and need to replace that relay. If not, then your problem is most likely that cooling fan switch in the bottom of the radiator.

    Good luck,

    nic2 ·
    hi Mike

    i started a thread on the corolla forum but haven't had any response.
    i read one of your posts and thought maybe you could help.

    whenever I turn the ignition to on my 1990 corolla, the cooling fan comes on and stays on untill I turned the car off regardless if it's a cold start or hot start.
    the fan even comes on when when i turn the key to the "on" position before starting. it goes off when i take the key out.

    i don't know much about repairs.
    from what i've read it the cooling fan sensor (switch) will cause this problem.
    there's often different terms used for the same part which can be confusing for a car dummy like me.
    is the 'cooling fan sensor' sometimes referred to as:
    a) cooling fan relay
    b) ECT sensor
    c)cooling fan switch

    i appreciate any help you can give me.
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