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    Auxiliary Fan & AC

    I have a few questions regarding the factory Auxiliary (electric) Fan and the Air Conditioning on E30's. I have seached a few times but have not found any definitive answers.

    My car is a 1990 325i and the fan clutch and water pump are less than a year old. I have noticed that my auxiliary fan does not run when I turn the AC on in my car. (this is also the time when the temp gauge will start to rise a little). Actually the electric fan will not turn on until the gauge is at the 3/4 mark on the gauge (this only happens at standstill with the AC on). Other than this my temp gauge stays around the 1/4 mark.

    My Questions are:

    1. Should the Aux Fan run whenever the AC is running?

    2. Are there connections that I should check?

    3. To me it seems that if my fan doesn't kick on till the 3/4 mark then the lower temp portion of the fan switch isn't functioning properly. Could this be a resistor problem? How do I check?

    Thanks in advance for any help/advice.

    #2
    My 87 325is is doing the same thing, aux won't kick on til almost in the red zone, like you it happens in slow/standstill traffic.. My tech said the fan should come on when a/c is turned on but offered no resolution to me at the time... Anyone got any ideas for this prob..... Thanks, tomwas
    Attached Files
    sigpicOn my 19th bimmer in 10 yrs.

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      #3
      According to my ETM, there is a leg at S228 that goes to the aux fan to kick it on when the AC is enabled. My 87 sedan does this just fine, as it should. This feeds a diode in the Power distribution box that energizes K1 (normal speed relay). This is done independently of the normal fan switch that works off of temperature.
      I saved 15% on my Bimmer parts by switching to ...



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        #4
        if the fan works when your temp gets to the 3/4 mark, then it should work when you press the a/c button. it sounds like your resistor is done since the low-speed isn't working. when the ignition is in the 'on' position, press your a/c button. If the fan does not come on, check continuity pre- and post-resistor. If you are not getting voltage post resistor, then the resistor is bad. If you do not get power pre-resistor, you have a short somewhere on the harness or one of your fuses blew. PM bimmerteck and tell him i sent ya. He helped me out a great deal when installing my aftermarket fan. He knows his shit.

        Originally posted by Ryan...
        It now emits a beautiful blue-ish yellow/green smoke from the exhaust?? No idea what would cause that color, but I assume its good.

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          #5
          Thanks for all of the info and quick responses...

          Comment


            #6
            Originally posted by Brandon12V View Post
            if the fan works when your temp gets to the 3/4 mark, then it should work when you press the a/c button. it sounds like your resistor is done since the low-speed isn't working. when the ignition is in the 'on' position, press your a/c button. If the fan does not come on, check continuity pre- and post-resistor. If you are not getting voltage post resistor, then the resistor is bad. If you do not get power pre-resistor, you have a short somewhere on the harness or one of your fuses blew. PM bimmerteck and tell him i sent ya. He helped me out a great deal when installing my aftermarket fan. He knows his shit.
            Thanks also, could you tell me where the resistor is located that you mention... tom
            sigpicOn my 19th bimmer in 10 yrs.

            Comment


              #7
              Originally posted by tomwas View Post
              Thanks also, could you tell me where the resistor is located that you mention... tom
              on the fan itself. follow the wires from the connector, and you will go right to it
              I saved 15% on my Bimmer parts by switching to ...



              Comment


                #8
                I'd also replace your thermostat if your temp is able to fluctuate between 1/4 and 3/4.
                Originally posted by Gruelius
                and i do not know what bugg brakes are.

                Comment


                  #9
                  The answer is almost certainly the resistor on the side of the fan, which is supposed to keep the fan running at slow speed. Bump the low speed fuse to the same as the high speed fuse and bypass the resistor.
                  2006 GMC Sierra 2500HD 4WD LBZ/Allison
                  2002 BMW M3 Alpinweiß/Black
                  1999 323i GTS2 Alpinweiß
                  1995 M3 Dakargelb/Black
                  - S50B32/S6S420G/3.91
                  1990 325is Brilliantrot/Tan
                  1989 M3 Alpinweiß/Black

                  Hers: 1996 Porsche 911 Turbo Black/Black
                  Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

                  sigpic

                  Comment


                    #10
                    Originally posted by nrubenstein View Post
                    The answer is almost certainly the resistor on the side of the fan, which is supposed to keep the fan running at slow speed. Bump the low speed fuse to the same as the high speed fuse and bypass the resistor.

                    I like the way you think....sound like a good solution till I source a replacement resistor.

                    Comment


                      #11
                      resistors are cheap. $25 man!

                      Originally posted by Ryan...
                      It now emits a beautiful blue-ish yellow/green smoke from the exhaust?? No idea what would cause that color, but I assume its good.

                      Comment


                        #12
                        Originally posted by nrubenstein View Post
                        The answer is almost certainly the resistor on the side of the fan, which is supposed to keep the fan running at slow speed. Bump the low speed fuse to the same as the high speed fuse and bypass the resistor.
                        This would be connecting fuse 13 to fuse 18 in the panel ?......
                        sigpicOn my 19th bimmer in 10 yrs.

                        Comment


                          #13
                          Originally posted by Brandon12V View Post
                          resistors are cheap. $25 man!

                          This is true, but it doesn't mean they have it in stock at your local parts store on Memorial Day.

                          Comment


                            #14
                            The a/c works better with the resistor bypassed, anyway.
                            2006 GMC Sierra 2500HD 4WD LBZ/Allison
                            2002 BMW M3 Alpinweiß/Black
                            1999 323i GTS2 Alpinweiß
                            1995 M3 Dakargelb/Black
                            - S50B32/S6S420G/3.91
                            1990 325is Brilliantrot/Tan
                            1989 M3 Alpinweiß/Black

                            Hers: 1996 Porsche 911 Turbo Black/Black
                            Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

                            sigpic

                            Comment


                              #15
                              Originally posted by tomwas View Post
                              This would be connecting fuse 13 to fuse 18 in the panel ?......

                              no, just replace the low speed fuse with one of the same rating (30A) as the high speed fuse. Easy peasy

                              And yes, the AC works better at low speeds with fan on high, especially here in AZ.
                              I saved 15% on my Bimmer parts by switching to ...



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