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Thread: fuse for fan blows?...

  1. #1
    Join Date
    Jan 2008
    Newcomerstown, OH

    fuse for fan blows?...

    I just hooked up a powermaster alt. 60/100amp. I have it wired direct to the battery master disconnect. Is this right?

    I have ran the original 37 amp alt. for 2 years with no problems with blowing fuses. I have dual electric fans from some unknown car, they work great. I have the wired with a relay and a 30amp fuse on the ground wire. What would cause this fuse to blow?? No shorts in the wire, I traced them and all looks good. Are the fans just getting worn out?? I am trying to tune in the timing on my motor, could being too far advanced put a strain on the electrical system?? I have an old MSD-7a with fixed curve timing computer, MSD billet locked out dist. I am also running a holley blue pump. any help is greatly appreciated.


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  2. #2
    Junior Member SHOW GUEST
    Join Date
    Jan 2009

    fuse for fan blows

    The fuse should be on the +(bat) side. It might not fix your current fan supply problem. But it will prevent wiring melt down. The higher amp alt. might be the thing that is the problem. Recheck all wiring routing and connections. If all else fails, start with the basics.

  3. #3
    Senior Member RACING JUNKIE
    Join Date
    Jul 2007
    Independence, Missouri
    Travis, I'll bet if you put your 37 amp alternator back in your car, it will quit blowing that fuse. Reason I think that, is your old alt. was probably marginal, in its ability too keep up with the amp draw on it. Your new hopped up electrical system now has more amps to draw from. I think your duel fans probably draw more than 30 amps, blowing the fuse. If you don't want to try a bigger fuse, you can protect the circuit with a fusable link. Most high amp circuits on an automobile are protected by fusable links, (starters, fans, Headlights, etc.) They are just getting more amps with the bigger alt. cause there are more available to draw from. Bet your fans spin faster, and your headlights are brighter too,with the bigger alt.
    Hope this helps, good luck
    No matter where you go, there you are.

  4. #4
    Senior Member EXPERT BUILDER
    Join Date
    Dec 2002
    spring creek nv.
    you need to run one 30 amp relay for each fan and put the fuse between the power supply for relay and relay.should do same on fuse.have each fan relay have it's own fuse[30 amp]another thing is once you do your fans this way and you blow one one fan fuse then that fan could be getting weak and causing more amp draw causing fuse to do go bad in time..if they start blowing fuses then that is a good sign that fan is bad..the bigger alternator will have no effect on fuses blowing.on some street cars i've built for myself and others i've gone frome stock 30 amp alternators too 110 amp alternators and never blowed any fuses..alternator only charges the battery..

  5. #5
    Senior Member DYNO OPERATOR
    Join Date
    Nov 2006
    Hot rod is correct !! I would say the same also.DR.When fans or whatever get old they draw more and can cause problems!!

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