Q: Heater only works on high

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The heater only worked on high . I actually had this same problem with my last two cars (ford ranger p.u - dodge ram van) I put a new resistor in and the heater worked fine for about a week, and now it only works on high again. Any suggestions where to look next would be appreciated. thanks tom. b.

My car has 76200 miles.
My car has an automatic transmission.

It sounds like you may have a faulty blower motor potentially drawing too much power from the resistor causing it to burn itself up. As you know, the individual blower motor resistor inside the pack are usually wire wound and they may fail by burning out from use, and may also fail due to mechanical stresses and vibrations typically found in an automotive environment. When a blower resistor is faulty, the fan will usually operate at one speed only, usually the highest speed setting possible. Sometimes, only some of the speed settings will be faulty while others might work. 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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