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Blowing fuse 20 with AC on

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    Blowing fuse 20 with AC on

    So I finally got my AC working again after sweating my ass off for the last two years but I now have a new problem that my be related. Symptoms are:

    1-When I run the AC it works fine with the blower on setting 1 or 2 but as soon as I turn the fan up to 3 it blows the 30 amp fuse.

    2-Today while driving I left the fan on position 2 and it worked fine for about 10 minutes then it blew with a small bit if smoke visible from the dash.

    Could this be a bad resistor on the blower motor? Could it be the blower swich has gone bad even though before this incident I could run the blower on any speed with no problems?

    Any suggestions are appreciated.

    #2
    My guess would be the blower motor. But it could be a problem with the resistor, switch, or wiring.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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      #3
      An update; I replaced the fuse again and for kicks put the fan on 4 or high to bypass all of the resistors in the switch. That fuse lasted about 10 seconds on high so I believe it is the resistors that have gone bad or it is the blower motor itself. I will have to tear into it next weekend when I have the time to work on it. Keep comments and suggestions coming.

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        #4
        #20 fuse melted my fuse box.. careful with those 30 amps! Blow the carbon dust out of the motor, or just replace it.

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          #5
          The odd thing is I can run the fan at any speed with no problems if I only have it on vent. Once I engage the AC is when it eventually blows the fuse depending on how high I have the fan speed. I called the BMW dealer yesterday to check on a switch and the guy th

          at worked there was surprisingly cool considering I am driving around a 21 year old car he offered to talk to the techs that work there and own e30s themselves to see if they had an idea. His initial thought was that the resistor has gone bad in the motor but after telling him it runs fine in vent or heat mode he said he would check with them again to see if they had any ideas. I will keep my progress posted in case someone else is having some of the same fun.

          I can't help but think it may have something to do with me having to bypass the slider controls to get the AC to turn on. Is there anyone else in Utah valley that might have an old one lying around that I could try?

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            #6
            Is the aux fan on the same circuit? if it is, that would explain it. The aux fan kicks in when the a/c is turned on.

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              #7
              # 20 is the low speed aux fan fuse. not the blower fuse.

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                #8
                Update and new dilema

                After much fun tearing the dash apart and dropping the little clips that hold the cables in place for the slider controls I have my fan speeds now all working. I had to replace the slider control which was about $75 at the dealer and get a new end connector to replace the ones that had partially melted when the thing first went out a few years ago. So far so good.

                Now my AC isn't cold at all which surprised me because a few weeks ago it was blowing nice a cold before the fuse would blow. So I either have a leak (which I kind of doubt since it had good pressure after sitting) or the systems pressure has just equalized from me hooking up the gauges to see how much pressure was left in the system.

                I think the system still has R12 in it but I am not sure I guess I need to take it to a shop and be prepared to be bent over. Is there a alternative to converting to R134? Has anyone tried Freeze 12?

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                  #9


                  I found a short which fixed mine.




                  1986 325es (69k) Garage Queen Buy It Now 10k;1986 325es (track rat) 2.7i How-To & 1.1/1.3Motronic UpGrade
                  1991 318is (daily driver) 1991 318is M42 Maintenance How-To;1989 325i (parts car)

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                    #10
                    Can of air is a good replacement for R12 all day just need a side can tape and a good ac gadge setup

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                      #11
                      Originally posted by spikernaut View Post
                      can of air is a good replacement for r12 all day just need a side can tape and a good ac gadge setup
                      wtf?
                      1990 M3

                      Comment


                        #12
                        All that for a 10yo thread
                        Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

                        https://www.r3vlimited.com/board/sho...86#post4944786
                        Alice the Time Capsule
                        http://www.r3vlimited.com/board/showthread.php?t=360504
                        87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

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