Heater relay fuse and blower

Posted by Natedaman_99, Dec 7, 2005
Newbie Forum - Beginner DSM modification questions and discussions. Common, repetitive, and general discussions will get dumped here from other tech forums. Unless you're a Probationary member you shouldn't post threads here.

  1. Natedaman_99

    Natedaman_99 Proven Member

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    Ok here is the problem. My blower for the heat/ac stopped working the other day. Checked the fuses and the heater relay fuse was blown. Replaced the fuse twice same thing happend blown fuse. It would work for a little bit and then just blow. When it would work i could get the blower for the heater/ac to work on 1,2,and 4 but not on 3. Anyone with a guess at this one?
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  2. BOBS90TURBO

    BOBS90TURBO Proven Member

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    Maybee the blower motor is going bad/locking up and causing resistance on the wire blowing the fuse, I have had 2 blower motors go bad, one slowly, the other stopped and never spun again.
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  3. Natedaman_99

    Natedaman_99 Proven Member

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    Thanks for the reply thats kinda what im thinking also since its like 10 years old and just all of a sudden it starts blown fuses. It picked the perfect time to go out yesterday morning it was 7 below zero when this happend. Well any other thougths on this would be great before i go and buy a new blower motor.
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  4. luv2rallye

    luv2rallye DSM Wiseman

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    If it's the 10A fuse, then the relay is bad (try swapping with another one same type). If it's the 30A fuse, then your blower motor is probably going (or you have a short in that line).
    This points to the blower switch, not the blower or the blower resistor. (FYI: Position 4 (hi) puts 12V on the blower. The other positions place resistors in series with the blower to lower the speed.)
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  5. Defiant

    Defiant DSM Wiseman

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    glorious Galt, California
    http://www.dsmtuners.com/forums/showthread.php?t=97686
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  6. Natedaman_99

    Natedaman_99 Proven Member

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    Its is blowing the 10A fuse.
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  7. Natedaman_99

    Natedaman_99 Proven Member

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    So you say resistor pack then Defiant?
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  8. luv2rallye

    luv2rallye DSM Wiseman

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    Blowing the 10A fuse has nothing to do with the blower resistors since they are on the other side of the relay (different circuit). It sounds like you have 2 problems - the 10A fuse blow and the switch position 3 problem. The switch position 3 problem is unlikely the resistors since positions 1 and 2 work which use the resistor for position 3 - if position 3 resistor was bad, positions 1 and 2 wouldn't work. Therefore it is more likely (almost has to be) a bad switch on position 3 for this problem. BTW you can test the blower motor by disconnecting the plug and applying 12V to it through a 30A fuse.
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  9. Natedaman_99

    Natedaman_99 Proven Member

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    Thanks luv2rallye the only other thing i have to add i guess is that since this yesterday now the blower will work and not blow the fuse if i use it at 1 or 2. It seems to just blow the fuse if i go over the 1 or 2 position. So do you think that it has to be the switch then?
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  10. luv2rallye

    luv2rallye DSM Wiseman

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    Minneapolis, Minnesota
    Well before you said it worked fine on position 4 (hi). But if you are now saying it blows the 10A fuse only on positions 3 or 4, then something is very wrong because the 10A fuse is supposed to be on the coil side of the relay which is not even on the same circuit as the resistors, blower, and switch. Are you sure you didn't put a 10A fuse in the place where it should have been a 30A one? The 10A should be 2nd from the left in the bottom row. The 30A should be the far right one in the middle row.
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  11. Natedaman_99

    Natedaman_99 Proven Member

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    Yes i have the 10A fuse in the right spot. At first i did say that it worked in the 1,2, and 4 position. Here is what happens if i leave it in the 1 or 2 position it works just fine and hasnt yet blown the 10A fuse. When i mess around with the control to move it to 3 the blower stops blowing and eventully will blow the fuse. When i put it on 4 it blows and it will blow the fuse eventully. Hope this makes a little more sense. Sorry.
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  12. luv2rallye

    luv2rallye DSM Wiseman

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    Test the blower motor by disconnecting the plug and applying 12V to it through a 30A fuse. This will do the same thing as putting it on position 4 (hi). See if the 30A fuse blows. If so, bad blower motor.
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  13. Natedaman_99

    Natedaman_99 Proven Member

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    Will do thanks again i will post back after the test.
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  14. Defiant

    Defiant DSM Wiseman

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    Welp, as with most of the stuff in DSMs, the switch is on the ground side. Since it's the 10A that keeps blowing, my first suspect is the switch itself- the 30A side, motor and resistors which control the motor are all electrically separated from the switch by the relay.
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  15. luv2rallye

    luv2rallye DSM Wiseman

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    Minneapolis, Minnesota
    The blower switch, relay, and relay wiring haven't been changed or tampered with have they? Is the A/C switch and defroster switch off (because they also go thru the blower switch and 10A fuse)? Does the blower go it's normal slow speed on position 1 and it's normal little faster on position 2?

    The only thing on the 10A fuse is the blower relay (coil side), the blower switch (but a completely different and separate circuit than the blower side resistors part of the switch), and the A/C & defrost switches. Assuming no wiring has been changed, with positions 1 & 2 working fine, the only thing that makes any sense as to why the fuse would blow would be if that other half of the blower switch (not the resistor half) is partially shorting to ground on positions 3 & 4. You could test this by temporarily cutting the blue/red wire at the blower relay or the blower switch OR cut the white/black wire at the blower switch or A/C switch or defroster switch. Note this will make your A/C (and defrost A/C) not work but if you need a test.... The only other thing would be if the relay coil is bad but only on positions 1 & 2 which doesn't make any sense. The relay is on when ignition is on. The blower turns on when the switch connects the other side of the blower to ground (thru resistors for positions 1, 2, and 3). Best bet is still the blower switch, second is the blower itself, third the relay.
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  16. Natedaman_99

    Natedaman_99 Proven Member

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    None of the stuff has been changed or tampered with at all. The AC and the rear defrost were not on at the time the fuses were blown. This morning again it worked fine on setting 1 and 2 and they both worked normal slow on 1 a little faster on 2. Also just to try it out i used the rear defrost with the blower on setting 1&2 and it worked just fine. I haven't been able to do much to get in there and look around no time until the weekend just looking for advice on what to look for so thanks defiant and luv2rallye.
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  17. luv2rallye

    luv2rallye DSM Wiseman

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    FYI: The defrost switch I'm talking about is connected to the defrost position of the air control lever to defrost/defog the windshield (switch is not visable). It turns on the A/C so dry air (instead of moist) will be blown to defog the windshield. The rear defrost switch turns on the electric heater wires in the rear hatch glass and is a different switch.
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  18. Natedaman_99

    Natedaman_99 Proven Member

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    Ok sorry my bad i thought you were talking about the rear defrost switch. Thanks again.
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  19. hoppe_4

    hoppe_4 Probationary Member

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    Hey guys old thread.. but did you fix it? Just got the problem a couple days ago exactly.. How'd you solve it?
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  20. AlaskanDsm

    AlaskanDsm Proven Member

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    Your best bet for now would be to follow the amazing instructions given by luv2rallye and attempt to diagnose the problem.
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