Blower motor cuts out

Heating / Cooling / AC

  1. moparkrazed

    moparkrazed Moparkrazed

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    Hey guys, I’m working on my 1975 Dodge Dart swinger, 318, auto, with factory ac (let me know if I missed anything). I finally found the correct blower motor wire and got my heater working today for the first time in five years... except the blower motor cuts off after 5 min of running. If I cut the blower motor off and let it rest after a few minutes it will cut back on and run for another five min or so. I’m getting power everywhere except after the pigtail where the blower motor connects to the harness going into the blower motor. When the motor is running I have power everywhere including at the pigtail going into the blower motor, when it cuts out I lose power at the pigtail only. What am I missing? Thanks for any help. Oh and my fan speed selector switch works when the fans running and the slider to select vent, ac, max ac, heat works as well when the motors working.
     
  2. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    "Jerry rig" a small gauge wire that you can put in various connectors---like the blower motor lead, the switch and maybe even the fuse panel, and tie that to a light so you can see where you are losing power. Also the blower has a ground pigtail.

    Don't discount the motor could have a problem, like, dry bushings
     
  3. Murray

    Murray FABO Gold Member FABO Gold Member

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    Could be a bad resistor.
     
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    • moparkrazed

      moparkrazed Moparkrazed

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      Thanks for the reply 67dart. I’ll give that a shot. I honestly wouldn’t be surprised if the motor is shot. It’s original to the car and hasn’t run in a long time. Thanks again.
       
    • moparkrazed

      moparkrazed Moparkrazed

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      Is the resistor on top of the heater box (has one wire attached) or is that the three spring looking things that regulate how fast the motor spins? Thanks for the post and help.
       
    • Murray

      Murray FABO Gold Member FABO Gold Member

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      Have not done it before, but before I yank the motor out I would by-pass that resistor, run the motor directly from the switch and eliminate that as a possibility. Yes, it is on the top of the box.
       
    • moparkrazed

      moparkrazed Moparkrazed

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      Ok cool I’ll give anything a shot. Thanks again.
       
    • Tooljunkie

      Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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      Sometimes a motor goes bad,creating excessive draw and overloading the circuitry.
      Switch overheating and circuit opens. If its not the motor, i bet you will find a hot or melted connector. Infra-red thermometer would come in handy.
       
    • moparkrazed

      moparkrazed Moparkrazed

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      Cool. I’ll try that too. Might have to make a quick trip to the tool store (which I never mind) haha. Just point the thermometer at the wire to get a reading?
       
    • Tooljunkie

      Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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      Yup, especially connectors.
      I have used mine to find drawing circuits,one was a radio amp that wasnt powering down, and on several occasions alternators drawing power.
      Glovebox with a bad lamp switch,whole glovebox door was hot compared to rest of dash.
       
    • moparkrazed

      moparkrazed Moparkrazed

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      Man that’s crazy. I’ll definitely have to pick one of those up. Thanks for the recommendation.
       
    • Tooljunkie

      Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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      Misfiring cylinder, point it at each manifold near exhaust port, cooler one is dead cylinder. Works very well on diesels too. Thats where i first saw it used.
       
    • moparkrazed

      moparkrazed Moparkrazed

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      That’s a pretty cool tool man. Definitely wouldn’t have ever thought about using it.
       
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