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Thread: Defroster Electrical Issue

  1. #1
    Member PETC's Avatar
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    Default Defroster Electrical Issue

    This morning on the way to work I noticed the rear defroster switch didn't seem to operate. No light and I couldn't hear a relay clicking. When I got to work I looked for the fuse but I couldn't find one for the defroster. Is it on another circuit that is labeled as something else?

    Additionally, the two larger 30A fuses for the window motors were ridiculously hot, like so hot I couldn't touch them. I removed them and re-inserted them thinking they weren't seated correctly and then I noticed the window defroster light turned back on. I figured it must have been related to the window motor circuit and went about my day.

    Come lunch time it wasn't working again. Fuses for windows still really really hot. Window motors all work as well as they ever have since I owned the car. The drivers motor does a strange thing where you can't use it too much in a short period of time... It's strange...

    Example:
    1. Window rolls down as expected.
    2. Immediately attempt to roll up window, window rolls up and then stops halfway.
    3. Window will not continue until you wait an indeterminate amount of time. If you wait long enough it will roll all the way up, if you're impatient and don't wait long enough it will only roll up a little, then you have to wait again.

    Very strange....


    Anyways, if any of you guys have any idea regarding literally any of this I would be appreciative.

    Cheers!

    EDIT: Took one of the hot fuses apart and realized it was in fact a circuit breaker. I think this explains my window motor issue... Still not sure on the defroster.

    EDIT 2: The other circuit breaker had some kind of buildup between the contacts that I think was preventing contact which would explain the defroster not working, harder to explain why it was so HOT! I figure if it was hot it would mean its making contact which means the defroster would work but it doesn't.
    Last edited by PETC; 04-25-2019 at 05:00 PM.
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  2. #2
    Member PETC's Avatar
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    Default

    Does anyone have any ideas? I'm still waiting on new circuit breakers to arrive but in the meantime I've tried a few 30 Amp fuses and they seem to hold for a while. The window circuit seems to not be an issue at all, but the POWER ACC circuit which powers the electric door locks and the defroster seems to have an issue. The door locks work fine when the circuit is complete, along with the defroster, both cycling on and off, but it seems that there's something else going on as after a few minutes the 30 Amp fuse will pop and (obviously) nothing on the circuit will work after that.

    All door locks move fluidly with little to no resistance and I never leave the defroster on when testing. If anyone has any ideas I'd love to hear them.
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  3. #3
    Member PETC's Avatar
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    Default

    I kept stubbornly throwing 30A fuses at the problem and I think I've figured it out! I put another fuse in and then realized that the power recline seats were on that circuit too. I tested them for functionality and they all worked so I was stumped. I leaned over looking in the glovebox waiting for the fuse to pop but it never did.... Defeated I sat up and leaned back in the drivers seat annnd POP it went. So I put in another fuse and then leaned back in the seat annnd POP it blew again. So now I knew the short was in the wiring for the power recline on the drivers side. I unplugged the seat until I can fix the wiring and I think the problem is solved.

    Only time will tell, but I'm optimistic. I'm sure you guys would have helped out, so even though I think the issue is fixed I'll say thank you. Only took me five fuses to figure it out!

    Cheers!
    Last edited by PETC; 04-27-2019 at 07:25 PM.
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  4. #4
    Senior Member CorvairGeek's Avatar
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    I haven't opened an A-body seat yet, but I can see the foam breaks down and starts pushing our the bottom of the seat frame though the support wires. I don't recall if the motor is inside the seat bottom foam on either side, but I'll bet there is a spot that can wear through the wiring and cause a short. Good way to start a fire too.
    Jerry

  5. #5
    Member PETC's Avatar
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    Luckily the short is directly after the connector. A thin piece of support wire under the seat had worn through the wiring loom cover and the insulator. Once the wiring is repaired and the wire it was rubbing against has some padding on it it should never happen again and the problem should be solved. Thanks!
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  6. #6
    Senior Member CorvairGeek's Avatar
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    I should probably take a look at the seats on my '92. It doesn't have power windows or a rear window defogger, so it might take longer to notice if developed the problem.
    Jerry

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