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    aux fan not coming on???

    Ok, did a big search yesterday, but found conflicting information.
    So here is the situation. Went to the ac shop this week and had the AC checked and filled.
    Runs nice and cold, but the guy at the shop said my clutch fan was not coming on and the aux fan was not coming on so the pressures in the system were too high to use in stop and go traffic...fine if you are going down the road::::)))
    So I check the fan switch, jumped it and the fans work, the clutch fan does engage, I can see it happening when I start the car and once it warms up.
    The information I got says it is the sensor on the radiator, so I replaced it no fan when I turn on the AC.
    So here is my question:)
    Some say the fan on low is suppose to come on when you turn on the AC, mine is not doing this...however, I do remember it turning on while pulling into the driveway after driving around in somewhat warm weather; Spring:)
    Some say the fan turns on when the temp reaches 91/99
    Now my car is in the garage running at operating temp, but it is cool outside and little load on the engine other than the AC is running.
    I would think you want the fan on if the AC is running and the engine is hot!!! not just come on because the AC is turned on??
    Also, my car runs just below the middle mark on the temp gauge no matter what the temp. Has never overheated, so I am thinking the clutch fan is working....
    Sorry for the long post, but maybe we can help more people who have the same problem.
    thanks for any questions, information, help, etc.
    jm

    #2
    well?

    I think it is the resistor. I switched the relays and nothing happened. Did the 30amp fuse in the #3 position, nothing...only thing left is the resistor....only problem is I have an m-tech spoiler in the way:)
    jm

    Comment


      #3
      99% likely it's the resistor.mjust connect both ends together to bypass it and bump your low speed fuse to 30a. The aux fan should ALWAYS come on when your compressor is running and it will also kick on when the temp gets high which should never happen.

      Test the fan clutch with a rolled up magazine and if it bad replace it too.
      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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        #4
        :)Thanks

        So just connect both wires to the same post? and that will bypass the resistor?
        Thanks for your input. Will try that next.
        thanks,
        jm

        Comment


          #5
          Originally posted by 2002jm View Post
          So just connect both wires to the same post? and that will bypass the resistor?
          Thanks for your input. Will try that next.
          thanks,
          jm
          Correct but you need to uprate the fuse as well.
          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

          Comment


            #6
            thanks

            Yes, the low speed is 15 and the high is 30.
            So put a 30 in #3 spot:)
            thanks,
            jm

            Comment


              #7
              Do you guys think doing this would get power to go to the compressor? If the fan comes on when you turn on the A/C? Right now my fan never comes on - A/C or hot engine. New resistor. Looks like the harness that goes to the aux fan never gets power when jumping the radiator temp switch harness. And I don't hear relays clicking. I made sure the temp switch is getting power. Simply a matter of bad aux fan relays?
              Last edited by usualdeviant; 07-10-2016, 06:50 PM. Reason: me tarded

              Comment


                #8
                :)

                Relays should click. Put your finger on them as you turn the key on. They will click. I jumped my radiator sensor and the fan came on....only thing left for me to do is replace the resistor....now that is a pain, since there are no connectors; have to hard wire it in. I am not sure I want my high speed fan running all the time. If I were keeping the car, I would order a relay tomorrow.:)
                jm

                Comment


                  #9
                  The only reason not to bypass the resistor is of you can't stand the fan noise. I run a SPAL which, on high, makes less noise than a stock fan on low and it just makes so much difference in AC efficiency.
                  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

                  Comment


                    #10
                    Originally posted by jeffnhiscars View Post
                    99% likely it's the resistor.mjust connect both ends together to bypass it and bump your low speed fuse to 30a. The aux fan should ALWAYS come on when your compressor is running and it will also kick on when the temp gets high which should never happen.

                    Test the fan clutch with a rolled up magazine and if it bad replace it too.
                    My resistor has 3 wires; 2 red and one black. While battling the frozen screws I destroyed the resistor, so I just connected all 3 to the broken connector as shown below:

                    Click image for larger version

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                    Is this the way to do it? My condenser aux fan still doesn't come on when the AC snowflake is lit up (blower comes on low speed as normal), but when the radiator switches are jumped the relays kick and the fan runs on both speeds, so I know it works (I replaced fuse 3 with a 30 amp ahead of time). I'm not getting voltage at the pressure switches, but that's another story. ;-) From what I've gathered the aux fan should run even if the A/C control regulator/relay is defective.
                    1986 325ES

                    Comment


                      #11
                      you know your fan works so it's almost certainly wiring. I'd take those resistor wires apart and check polarity and voltage with the key on, off, ac on/off, then run a continuity check from the high and low fuses.
                      That should narrow it down
                      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

                      Comment


                        #12
                        There are 3 diff temp aux fan switches. Maybe you got the wrong temp? I know there there is like a 82 degree one, 91 degree and 99 or something like that.


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                        1991 318i 4dr slick top


                        Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
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