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99% of the time it is the heater resistor block, it is a bunch of resistors which gives you the different speeds. this is mounted close to the heater motor, pass side of the car. Usual cause of failure: water or snow inside the heater housing.

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โˆ™ 2006-05-18 21:58:41
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Q: Why does your heater fan only run on high speed?
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