1993 Sierra 1500 heater blower works sometimes

Discussion in 'GMC Truck Forum' started by donpg101, Dec 6, 2016.

  1. donpg101

    donpg101 Member

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    Recently my heater blower stopped working most of the time. It will occasionally turn on after driving for a while. When the heater is set to off and I push a setting I hear a thump coming from the passenger side floor, but no blowing. When I changed fan speeds I hear a clicking coming from the glove box. The truck is producing heat but not blowing from the vents. So far I have only changed the resistor, it looked like mice were using it as a toilet. Before I tear apart my dash I would appreciate a little guidance. This is my first time dealing with this type of issue. Thanks.
     
  2. scavanger

    scavanger Full Member

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    Couple of things here . could be the resistor,but usually that is just speed specific . The other thing is ,behind the glove box are some connections and a relay. the main power connection can get bad. Can heat up big time maybe cause an electrical fire. I would check that sooner rather than later.
    Oh can also be the fan switch but that is usually speed specific also.Gives you warning by not working on some speeds
     
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  3. poncho62

    poncho62 Full Member

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    Probably have a loose wire under the dash which is making contact every now and then. Gonna have to get under there and wiggle the harness around and see whats happening. Pull the glovebox out, the wiring for the blower etc is right there
     
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  4. donpg101

    donpg101 Member

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    I was able to get it to turn on by banging on what I assume is the blower motor. It worked for the duration of my drive but it did not stay on for my next trip. Do I need a new blower motor or might this just be a connection at the motor?
     
  5. leolkfrm

    leolkfrm Full Member

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    check the resistor and plug for burn marks, put 12v direct to the motor, both should answer your question
     
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  6. dirtrider73068

    dirtrider73068 Moderator
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    Most times if you tap the blower motor and it comes on then it its going bad or is bad and needs relaced, I had to change mine for this reason would work then not work hit it with your foot would come on, put a new one in works great.
     
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  7. kbrown11

    kbrown11 Full Member

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    Any luck? I would say disconnect the motor and using a multimeter check the plug that connects to the motor to see if you are getting power at the motor.
     
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  8. MikeG

    MikeG Full Member

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    #8 MikeG, Dec 14, 2016
    Last edited: Dec 14, 2016

    Relay & Resistor, On the resistor itself there is a coil pack for the LOW(er) speeds and a seperate coil for the HI. If one goes out you will lose the associated speed, resulting in no blower function. If one is replaced you should replace both as well as the plug connector to the Resistor. I had the same problem in my 96 K1500.
     
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  9. MikeG

    MikeG Full Member

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  10. dirtrider73068

    dirtrider73068 Moderator
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    I lost low speed on mine I just replaced the resistor, my connector and stuff looked fine. What happend to a just a speed switch whats the need for all this resistors and junk.
     
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