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Q: My AC does not always work. If I fiddle with the blower knob I can ususally get it to work on the lowest setting.

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My AC does not always work. If I fiddle with the blower knob I can usually get it to work on the lowest setting. And if i fiddle with it some more once in a blue moon I can get the higher settings on the knob to work. But they never work on the exact spot they are supposed to. Usually they end up half way between to setting numbers on the dash and a small bump can knock it out of wack. Also on the rare occasion I do get one of the higher settings to work if I shut off the car then restart it it usually stops working again. Can you tell me what I need to fix it?

My car has 104000 miles.
My car has an automatic transmission.

Hi There, It sounds like you may have a faulty blower motor resistor. The highest speed setting may still work because in most cars in the highest fan speed settings the current bypasses the blower motor resistor. In some cars, if the resistor is failed, the fan may stop working completely. Another reason a blower motor resistor may fail is when the blower motor has a mechanical problem or when a foreign object jams the blower motor fan blade and prevents it from spinning freely. This leads to increased current through the resistor and causes it to overheat and fail. I would suggest having an expert from YourMechanic come to your location to diagnose your system to determine what may be causing the fan not to work properly.

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