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Thread: heater always works even when the cars off

  1. #1
    Hybrid booster
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    Question heater always works even when the cars off

    1989 shadow
    when you turn the ignition off (with the heater on) the heater stays running,
    when you pull the fuse for the heater it also still works even with the car off
    the heater control and variable speed all function properly, just it works all the time and the ignition being off doesn't stop it

    tried replacing ignition switch ( no change )

    is there something thats supposed to turn it off that may have went bad ? like a resistor or relay or something because i i cant figure it out

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: heater always works even when the cars off

    I had extensive problems with my 90 Shadow when it came to the heat. In 90 there was a fuse for it, but it ran straight to the heater control panel and then to the blower motor. My blower motor pulled so many amps that it would kill the ign switches in short order if the heat was used.

    I just checked the 90 FSM diagrams from when I had this problem. They're located in my gallery. It indicates that fuse 7 should stop the blower from functioning when removed. Other than the motor being backfed somehow, or a short in the wiring to power which would be odd, I can't think of anything which would cause this condition if you've pulled the actual fuse. I suppose I could be reading the diagram incorrectly, but I don't believe I am.

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    http://www.turbo-mopar.com/forums/photopost/showgallery.php?cat=951

  3. #3
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    Re: heater always works even when the cars off

    i have a feeling the dash harness may be done, something is definitely back feeding it, i played around with it more and swapped out the heater controls and nothing changed, then i decided to pull all the fuses one by one untill the blower stopped and the power locks fuse did it,\ so the problem is the power locks is somehow feeding into the blower motor, maybe2 wires melted together either way it might just be easier to swap the dash harness
    Last edited by Fox; 12-09-2017 at 12:35 AM.

  4. #4
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: heater always works even when the cars off

    Quote Originally Posted by Fox View Post
    i have a feeling the dash harness may be done, something is definitely back feeding it, i played around with it more and swapped out the heater controls and nothing changed, then i decided to pull all the fuses one by one untill the blower stopped and the power locks fuse did it,\ so the problem is the power locks is somehow feeding into the blower motor, maybe2 wires melted together either way it might just be easier to swap the dash harness
    I solved my problem by relaying the blower motor. Perhaps that would help you out? Run a few new wires and you should be all set.

  5. #5
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    Re: heater always works even when the cars off

    yea i would but i have the opportunity to replace it with a clean harness, with the 1 wire being crossed already id hate to have a more serious issue later on

  6. #6
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: heater always works even when the cars off

    Well, if you have access to a nice, replacement harness I say go for it. The under dash harnesses don't come up often at all.

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