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Q: Cooling fans

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My car has 2 fan spends hi and low... Only the low speed comes on and that's only if I turn the a/c on... I've changed relays fuses temp switch and thermostat... I bleed system burped it and flushed.... But the only way I can get the high fan to kick on is if I unplug the temp sensor which I replaced twice just in case the first one was faulty ... What could be the problem?????

My car has 145000 miles.
My car has an automatic transmission.

This can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. I would suggest having an expert from YourMechanic come to your home to diagnose your cooling system.

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