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    #1

    Aux Fan switch location

    Since its warmed up here quite a bit, I decided to run the A/C on the car today. It never really got cool, but I also never heard the aux fan kick on. That said, I can't say I've ever heard the fan kick on since I've had it. I tested the fan, and it does work. Sitting in the garage running, the motor got plenty warm and should have kicked the fan on, but it didn't. My question is, where is the switch that controls it located? On Real OEM it looks like it should be on the drivers side of the radiator some place, but there is nothing there.

    I'd love to find this thing and get it replaced so I have both A/C and so I don't cook the car. It looks to be a brass two prong guy, but I can't find anything like that any where in the engine bay. The car was built 10/87 if that makes any difference.

    Thanks,
    Will
    '59 Alfa Romeo 101.02 Giulietta Sprint
    '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
    '69 Datsun 2000 roadster Vintage race car
    '88 BMW M3
    Tags: None
    #2
    It's on the thermostat housing. There is a three prong connector which activates the fan at a given temp.

    The two prong connector shuts off your ac if it gets to hot.

    Comment

      #3
      Originally posted by mavrikno13764 View Post
      It's on the thermostat housing. There is a three prong connector which activates the fan at a given temp.

      The two prong connector shuts off your ac if it gets to hot.
      interesting i am wondering if this is causing my compressor to stop running... how do i bypass the two prong connector?

      Op sorry to thread jack...

      Comment

        #4
        Ah ok got it. I can't find the 2 pronged one anywhere. I found the 3 prong. That looks like a bit of a pain to replace. I thought that was it.

        Just to double check before I run out and buy a new switch, here are the symptoms. A/C on, the aux fan doesn't kick on. With the car running warm the fan doesn't kick on. Power direct to the fan at the plug, the fan kicks on (hence my reasoning that the fan is fine.) Is there anything else I should be looking for?

        Thanks,
        Will
        '59 Alfa Romeo 101.02 Giulietta Sprint
        '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
        '69 Datsun 2000 roadster Vintage race car
        '88 BMW M3

        Comment

          #5
          Originally posted by lore2486 View Post
          interesting i am wondering if this is causing my compressor to stop running... how do i bypass the two prong connector?

          Op sorry to thread jack...
          You can try to bridge the two connections or just unplug it. I don't recall how that switch works... Sorry.

          Originally posted by BlackbirdM3 View Post
          Ah ok got it. I can't find the 2 pronged one anywhere. I found the 3 prong. That looks like a bit of a pain to replace. I thought that was it.

          Just to double check before I run out and buy a new switch, here are the symptoms. A/C on, the aux fan doesn't kick on. With the car running warm the fan doesn't kick on. Power direct to the fan at the plug, the fan kicks on (hence my reasoning that the fan is fine.) Is there anything else I should be looking for?

          Thanks,
          Will
          The switch should be on the otherside of the three prong switch.

          The ac switch should automatically kick on the aux fan...
          If that isn't working, the problem I had was the diode inside the fuse box was broken... I resoldered it for less then $3. But first and for most, check your fuses and relays.
          You should be able to hear them click on when you turn your ac on.

          Hope that helps.

          Comment

            #6
            With the A/C on I can hear the relay kick on, and the compressor kicks on. The fan however doesn't. The fuses all look good. Where is the diode in the fuse box? All the diagrams of the fuse boxes I've found are a bit on the vague side as to what a couple of the relays in there actually do. I know two are for the headlights, one or two of them for the fog lights but I don't have a clue what the others do.

            Thanks,
            Will
            '59 Alfa Romeo 101.02 Giulietta Sprint
            '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
            '69 Datsun 2000 roadster Vintage race car
            '88 BMW M3

            Comment

              #7
              Originally posted by BlackbirdM3 View Post
              With the A/C on I can hear the relay kick on, and the compressor kicks on. The fan however doesn't. The fuses all look good. Where is the diode in the fuse box? All the diagrams of the fuse boxes I've found are a bit on the vague side as to what a couple of the relays in there actually do. I know two are for the headlights, one or two of them for the fog lights but I don't have a clue what the others do.

              Thanks,
              Will
              There are a few screws that hold the top of the fuse box together.
              When you unscrew it and take the top off, you will see a bunch of wires.
              Among all the wires you will see a black plastic casing with wires coming out of both ends.
              This case holds the diode to the Aux fan. I unhooked mine from the wires and cracked open the case to see a diode that has completely shattered... Went to my local Marvac (I think radio shack will do the same), bought a bag if diodes for $3, and they offered to solder it on for me. Replaced the diode (IN THE RIGHT DIRECTION, please note the orientation!) and WALA! Aux fan started working again.

              Comment

                #8
                Do I have to pull all the relays and fuses to take the top off? I'll take a look-see this afternoon after work.

                I have a soldering and desoldering iron so I should be good to go if I need to replace the diode. It also sounds like I'll be going for a bike ride to go get it since I'll have the car apart. I wouldn't trust the people at the local radioshack to do so much as solder the end of a wire. They are totally clueless.

                Thanks,
                Will
                '59 Alfa Romeo 101.02 Giulietta Sprint
                '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
                '69 Datsun 2000 roadster Vintage race car
                '88 BMW M3

                Comment

                  #9
                  You may have to remove one just to get to a screw, but you don't have to remove anything otherwise.

                  Not sure about RadioShack employees but, Marvac people are great :)

                  Comment

                    #10
                    I did a little looking and this is all I could find that was remotely close to your discription


                    Under the cover was a diode, but it looks good. I didn't see any damage to it at all. Sounds like I'm back to the two switches. On those, one is the Double temp switch p/n 61311378073 and the "Temp Switch" p/n 12632241342, the first being the 3 prong and the 2nd being a two prong. Do I have my parts right? The parts being #s 18 and 19 in the diagram.


                    I'm thinking its got to be one or the other of these switches.

                    Thanks for the help,
                    Will
                    '59 Alfa Romeo 101.02 Giulietta Sprint
                    '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
                    '69 Datsun 2000 roadster Vintage race car
                    '88 BMW M3

                    Comment

                      #11
                      Whao! That looks super janky! Mine was covered with a black platic.
                      You are correct 18 being the fan switch and 19 being the ac cut off.
                      If you search, you can find a diagram that shows which relays click on.

                      Or you can bridge the connections on #18 plug. One of the three is a hot wire. The others are simply to activate the relay for different fan speeds. Jump the wires and the fan should come on.

                      Comment

                        #12
                        I tried jumping the plug directly off a battery (I love my 13 lb racing battery from the race car. It comes in handy) but I couldn't get the fan to kick. Perhaps I had a lousy connection. I couldn't get anything to kick on, however I don't think I had the motor running or the a/c on at the time.

                        So I can bridge the harness part of the plug its self by finding the hot lead and running a jumper over to either of the other two leads? I know one is a low speed and the other a high speed. If this doesn't work, can I assume that its the two prong switch that isn't working or do I have another gremlin elsewhere in the harness?

                        thanks,
                        Will
                        '59 Alfa Romeo 101.02 Giulietta Sprint
                        '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
                        '69 Datsun 2000 roadster Vintage race car
                        '88 BMW M3

                        Comment

                          #13
                          Yes, you can bridge the harness part of the plug.
                          If I remember correctly, the two prong switch has nothing to do with aux fan, only with the AC.

                          Sounds like you have another gremlin...

                          Comment

                            #14
                            Originally posted by mavrikno13764 View Post
                            Yes, you can bridge the harness part of the plug.
                            If I remember correctly, the two prong switch has nothing to do with aux fan, only with the AC.

                            Sounds like you have another gremlin...
                            Possibly, but perhaps not. The a/c is sort of cold, and gets warmer if the car is just sitting there. It cools down some once I start driving. With the fan running it should cool down more due to more air passing over the heat exchanger. I think the system might need a recharge perhaps, but until I have the fan running I'm not going to worry about that.

                            Does it matter if the heater core is bypassed? My heater control valve died a couple months ago and I haven't gotten around to taking that mess apart to fix it yet. I'm guessing no it doesn't but then this is a modern car (compared to what I'm used to working on) so perhaps it does.

                            I'll play with this a little later after I get back from my bike ride.

                            Will
                            '59 Alfa Romeo 101.02 Giulietta Sprint
                            '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
                            '69 Datsun 2000 roadster Vintage race car
                            '88 BMW M3

                            Comment

                              #15
                              I ran a jumper between the plugs in the three prong, and got the fan to kick on and off with the a/c button. The a/c isn't really any colder, but at least the fan runs. The odd thing is that the temp gauge didn't seem to be any cooler. It appears that the 3 prong switch is the guilty party there.

                              Thanks for the help,
                              Will
                              '59 Alfa Romeo 101.02 Giulietta Sprint
                              '69 Alfa Romeo 105.51 1750 GTV (R.I.P)
                              '69 Datsun 2000 roadster Vintage race car
                              '88 BMW M3

                              Comment

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