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I'm stupid, whay doesn't this work?

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    I'm stupid, whay doesn't this work?

    Got a 2 speed fan. 3 relays.

    I wired it so that an adjustable thermostat gets acc power and triggers a relay for the low speed fan. The second relay is connected to the AC compressor. The third relay is wired normally closed in between the thermostat and the low speed relay. It is connected to the AC relay so it should open the 3rd relay and not have both fans running at the same time...it doesn't work.
    Builder/Owner of Badass Panther Wagons

    Busy maintaining a fleet of Fords

    #2
    Originally posted by mrltd
    It is connected to the AC relay so it should open the 3rd relay and not have both fans running at the same time...
    ther are a lot of ways to be 'connected to' a relay - Im gonna need a diagram or a very detailed explination of the wiring at all 4 or 5 terminals of each relay to help.
    Its probably just somthing you didnt account for in the logic of your relay circuit and could be fixed with a diode somewhere.
    Pete ::::>>> resident LED addict and CFI defector LED bulb replacements
    'LTD HPP' 85 Vic (my rusty baby) '06 Honda Reflex 250cc 'Baileys' 91 Vic (faded cream puff) ClifFord 'ODB' 88 P72 (SOLD) '77 LTDII (RIP)
    sigpic
    85HPP's most noteworthy mods: CFI to SEFI conversion w/HO upperstuff headers & flowmasters P71 airbox Towncar seats LED dash light-show center console w/5 gauge package LED 3rd brake light 3G alternator mini starter washer/coolant bottle upgrade Towncar power trunk pull underhood fuse/relay box 16" HPP wheels - police swaybars w/poly rubbers - budget Alpine driven 10 speaker stereo

    Comment


      #3
      I tried a diode in a few places. Didn't help any. Damn,thought that was pretty detailed....here's a rough schematic...
      Attached Files
      Builder/Owner of Badass Panther Wagons

      Busy maintaining a fleet of Fords

      Comment


        #4
        Actually you only need 2 relays to do what you want.
        **edit**
        ok that schematic isn't right. Let me see if I can hack this up in paint and make it not retarded.

        See if you can read this. Its my horrible chickenscratch scanned in. I'll see if I can do this up in some more legible format later



        I'm pretty sure that should work. Relay 1 has the normally closed contact (87a) going to the low speed, and the normally open going to the high speed. The switched contact (30) gets its power from Relay 2. Theory of operation is something like this

        Relay 1: not energized
        Relay 2: not energized
        No fan runs

        Relay 1: not energized
        Relay 2: energized
        Low fan

        Relay 1: energized
        Relay 2: energized
        High fan

        Relay 2 must have power for the fan to work. The only way high fan will come on this way is if the AC is switched on. This will supply power to both R1 and R2. If the fan controller comes on, it supplies power only to R2. You can flip around the fan outputs so AC runs on fan low and the fan controller kicks into fan high if you'd like. SImply reverse connections on 87 and 87a on the top relay.
        Last edited by gadget73; 06-25-2006, 06:29 PM.
        86 Lincoln Town Car (Galactica).
        5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

        91 Lincoln Mark VII LSC grandpa spec white and cranberry

        1984 Lincoln Continental TurboDiesel - rolls coal

        Originally posted by phayzer5
        I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

        Comment


          #5
          Makes sense...less relays are better.

          The problem I saw with that other schematic from the S10 forums is that it looked like the low fan was on constantly...I spent way too much time messing with that friday....
          Builder/Owner of Badass Panther Wagons

          Busy maintaining a fleet of Fords

          Comment


            #6
            Yeah, I realized that after I looked at it more. That might work for some fans, but I know if you try and energize the high and low contacts on a Ford fan it just sits there and sucks up crazy power. Tried it on mine and the ammeter on the 30 amp supply slammed and voltage dropped to about 10v from 15. Another issue with that schematic I drew up is that its not keyed power. Depending on the setup of the fan controller, it could stay running after the engine is off, but that would be easy enough to fix. Either make the fan controller itself run off key power, or wire in a third relay between the battery + and control that with keyed power.
            86 Lincoln Town Car (Galactica).
            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

            91 Lincoln Mark VII LSC grandpa spec white and cranberry

            1984 Lincoln Continental TurboDiesel - rolls coal

            Originally posted by phayzer5
            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

            Comment


              #7
              are you using single pole double throw relays? they have two outputs - one is always a closed circuit, untill the relay is energized - then the relay 'switches' the output over to the other terminal.

              With these, all youd have to do is power the thermostat controlled relay through the normally closed circuit terminal of the AC relay. This way, whenever the AC relay kicks on, the low speed fan will shut off, since the thermostat controlled relay is no longer getting a power supply.

              This is how I wired my foglamps to go off when the high beams come on.
              Pete ::::>>> resident LED addict and CFI defector LED bulb replacements
              'LTD HPP' 85 Vic (my rusty baby) '06 Honda Reflex 250cc 'Baileys' 91 Vic (faded cream puff) ClifFord 'ODB' 88 P72 (SOLD) '77 LTDII (RIP)
              sigpic
              85HPP's most noteworthy mods: CFI to SEFI conversion w/HO upperstuff headers & flowmasters P71 airbox Towncar seats LED dash light-show center console w/5 gauge package LED 3rd brake light 3G alternator mini starter washer/coolant bottle upgrade Towncar power trunk pull underhood fuse/relay box 16" HPP wheels - police swaybars w/poly rubbers - budget Alpine driven 10 speaker stereo

              Comment


                #8
                Yeah, that schematic is SPDT relays, standard Bosch ones that are avaliable anywhere. The way its wired, the low is on the normally closed contact, and the high is on the normally open, so putting power to the top relay flips it from high to low. The bottom relay just takes the load off the fan controller itself and switches +12vdc on and off. The diodes are there to keep the fan controller from kicking the AC on, and to keep the AC from feeding voltage backwards into the fan controller.
                86 Lincoln Town Car (Galactica).
                5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                91 Lincoln Mark VII LSC grandpa spec white and cranberry

                1984 Lincoln Continental TurboDiesel - rolls coal

                Originally posted by phayzer5
                I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                Comment


                  #9
                  OK, well remember the schematics for Scottfest when you guys clean up the wiring in the superlinc...

                  I dunno why I overcomplicated it so much...prolly because I was tired as hell..
                  Builder/Owner of Badass Panther Wagons

                  Busy maintaining a fleet of Fords

                  Comment

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