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Auxilary fan popping #3 fuse..

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    #1

    Auxilary fan popping #3 fuse..

    So heres one thats been buggin me the past few days. Just got the A/C system put back together (new compressor and some o-rings), and we charge the system up, it holds great. Turn it on, the compressor kicks in but the auxiliary fan doesnt come on.

    So we check power, the green/black striped wire gets power when the a/c switch comes on. Im assuming the original fan took a shit (it had a lot of resistance when trying to spin the fan by hand), so I went out and got a brand new one (OEM BMW part too btw). Spent an hour getting it into place, plug it in, and it now starts popping the #3 fuse (15A) the second u push the AC switch on..

    is it even common to get a bad fan? It already came wired with a new resistor and everything...is there anything else to check before i really isolate it to the fan? When I unplug it, it doesnt blow the fuse anymore, and if I use a circuit tester and probe the fan itself, it pops the internal breaker on the circuit tester...

    Im so close to finally getting the AC to work completley, just one hurdle after another...
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    #2
    probe the power leads and see if there is a short somehwere also check the switch on the radiator to make sure those wires arent damaged

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      #3
      Is the fan fuse only 15A? I thought it was higher than that.

      Might be a short elsewhere. How's your fusebox wiring? Or temp switch wiring?
      89 325is track project / 05 x5 / 99 M3
      E30 stuff for sale | Parts I'm looking for

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        #4
        Fuse 3 does indeed run only the "normal speed" fan, between the relay and the fan resistor.

        If you look at page 6454-1 of the ETM (you can find that at www.wedophones.com, follow the links for "manuals" then "automotove") you will see the diagram pretty easily shows the path.

        I would guess either shorted resistor or draggy fan.

        GL!
        Luke

        Closing SOON!
        "LAST CHANCE FOR G.A.S." DEAL IS ON NOW

        Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

        Thanks for 10 years of fun!

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          #5
          Originally posted by bmwpower View Post
          Is the fan fuse only 15A? I thought it was higher than that.

          Might be a short elsewhere. How's your fusebox wiring? Or temp switch wiring?

          #3 is the low speed, which is only 15...for shits and giggles I popped a 20 in there to see what it would do and it popped that right away too.

          Its not breaking it just a little bit..its like blowing the inside of the fuse apart.

          The fan is brand new (comes wired with a new resistor), I went and got another one today and tested it with a circuit probe, fed power and ground to it and it works just fine on both high and low. The second you plug it in, it pops.

          The other guy I work with has a tool that i can put into the fuse slot and see how many amps its pulling at any given moment. Im going to disconnect the fan and plug the fuse tester in, and see if something else is running on the circuit that is pulling maybe 5-10 amps.

          I checked the diagram on Alldata (since it was there at the shop) and the low speed fan wire runs straight from the fuse directly to the fan. I wonder if it is backfeeding through the high fan relay somehow on the other line, but if that relay is stuck on, then the temperature switch that controls the on and off of the high speed relay is stuck on.

          ugh. I hate electrical issues. That and my gauge cluster is starting to fail as well, even though I soldered all the broken terminals....

          Comment

            #6
            Is the wiring in correctly? I know it sounds simple but some time in hast we wire things backwards accidentally.
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            Comment

              #7
              Originally posted by M-technik-3 View Post
              Is the wiring in correctly? I know it sounds simple but some time in hast we wire things backwards accidentally.
              This is what I would go with. Even if it plugs in only one way, make sure it isn't wired backward from the factory. You said you put 12V directly to the +/- on the fan. I assume you put + to + and the fan turned the correct direction?

              Comment

                #8
                yeah i double checked the wiring. It plugs in one way, and I made sure each lead goes to the right one. I will double check it again tomorrow as I was in a little bit of a rush tonight..

                Comment

                  #9
                  very old post but I found it because I had the same issue. Here is a resolution. Check your new fan (yes even OEM) because in it's C113 connector, High speed and Low speed wires were reversed. Which made High side designed for 30A fuse being powered by through 15A fuse from low speed relay

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