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Technical Wiring fan question

Discussion in 'The Hokey Ass Message Board' started by atomickustom, Sep 26, 2019.

  1. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

    I know electric fans aren't traditional but my otherwise traditional car (see avatar) has one due to a series of rookie mistakes I made when building it pre-HAMB.

    So, big ass pusher fan. Works fine EXCEPT I bought a fancy controller that is supposed to turn it on at half speed at one temp and then go to 100% at a higher temp. Sounds great in theory but it is not really working out. No matter how much I adjust it I get 100% fan too soon OR no fan when hot. I'm ready to ditch the stupid controller and just hook up a manual switch.

    Now to my questions: can I just run battery + to fan (it's already wired this way) and use a heavy-duty toggle switch to ground the fan? I would just be replacing the fancy-ass controller with a manual switch.
    Where would I put a fuse?
     
  2. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

  3. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,454

    Bandit Billy
    ALLIANCE MEMBER

    Fans draw a lot of juice! The switch you speak of needs to control a relay that will supply the power, don't run the juice through the toggle. I (they may recall my alliance tags) have 2 cars with electric fans on them, and both are wired differently.
    One has a controller like you mentioned that controls 2 fans on my 442. It can turn one fan on or both and it has worked flawlessly for 10 years now. The car was my 1/8th mile drag car and the fans were needed to solve a huge heating issue that was cooking that poor olds.
    The other is my 34 with a blown flathead, it has a spal fan in a shroud with a thermostat (180) that cycles the fan when needed. Even with a fresh motor, in traffic on hot summer days this year she never dropped a drip. Both fans are pullers, both on relays, both are spal fans, neither are installed on the core (both are installed in shrouds that are supported by the radiator frame.

    The HAMB isn't a fan (pun intended) not should they be, not traditional. But you have to be able to drive your car and overheating is embarrassing when you get honked at by passing teslas and priii.
     
  4. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

    So I need a relay even if the switch is grounding the circuit? That's what I was a afraid of. I pulled out what I had before to make way for the controller.
    Maybe before I give up on the Maradyne controller I need to try a different sending unit?

    The most annoying part is I got myself into this situation to solve a relatively MINOR cooling problem. For years I ran a flex fan with a small pusher as an auxiliary. Then ONE TIME I overheated in a drive through and decided to upgrade to an aluminium radiator, which was thicker and left me no room for a mechanical fan at all, which then led to upgrading the small electric pusher to a big one, which I should have just wired in and forgot about but I figured since I'm upgrading everything else I might as well go for a fancy controller...and the rest is aggravating history. Driving this car is now frustrating (when the fan kicks in 100% and the temp's only 170) or filled with anxiety (when I'm sitting at a red light on a hot day and the temp climbs to 220 and the fan still hasn't kicked in!).

    V-8 + '49-'54 Chevy engine compartment + A/C [it's routinely 100 degrees here in the summer] = cooling issues. I mounted the engine too far forward to install a big mechanical fan, and since I replaced the radiator I don't have room for ANY mechanical fan or an electric puller. Live and learn...
     
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  5. G-son
    Joined: Dec 19, 2012
    Posts: 560

    G-son
    Member
    from Sweden

    The switch needs to be able to handle the current going through it, no matter where in the circuit you put it. I don't know how much current the fan needs, but chances are you'll want a relay.
     
  6. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

    Guess I will be buying a new relay then! Thanks fellas.
     
  7. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,454

    Bandit Billy
    ALLIANCE MEMBER

    And add an override switch that turns the fan on/off at your command in case the controller fails. Both my cars have overrides just in case.
     
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  8. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,179

    gimpyshotrods
    Member

    Just get a temperature switch, and a relay. If you want a manual switch, wire it so it also turns the fan on, not so it's the only way to turn it on.
     
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  9. hotrodjack33
    Joined: Aug 19, 2019
    Posts: 131

    hotrodjack33
    Member

    Years ago I built a 40 ford pickup and wired a cheap electric fan directly, without a relay, to the start side of the ignition so it would be on whenever the truck was running. Worked great until you would try to turn the truck off. Seems that the fan motor would act like a generator and send current back through the ignition and keep the truck running/dieseling until the fan stopped spinning. Took a while to figure that one out:eek:
     
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  10. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

    Good advice, good point!

    Are temp switches all about the same or is there a particular brand to get?
     
  11. gimpyshotrods
    Joined: May 20, 2009
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    gimpyshotrods
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  12. egads
    Joined: Aug 23, 2011
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    egads
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  13. WZ JUNK
    Joined: Apr 20, 2001
    Posts: 1,609

    WZ JUNK
    Member
    from Neosho, MO

    I like these from Speedway.Flex-A-Lite-31147-Adjustable-Electric-Fan-Control-Kit,2350.html. The instructions say that you can use these without a relay but I use them to trigger a relay just to be safe. The back up switch is not needed if your controls are working correctly, but it does not hurt to have an extra manual control.
     
  14. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

  15. fordflambe
    Joined: Apr 9, 2007
    Posts: 398

    fordflambe
    Member

    Before you give up, is your fan motor a single speed or dual speed? My dual speed fan has three wires out of the fan motor. Ground, High speed, and low speed. I use Dakota Digital controller on my two speed fan and it works great. I have not seen any controllers that will provide split voltage (drop voltage) to control speed on a standard VDC motor, but i have not researched all controllers..........I may actually learn something here.

    The fan i use with my Dakota Digital controller is Cooling Components........These components make a "jamb-up" set up for cooling!
     
  16. Good info above^^^^^ BUT- I like to control my fan myself, and leaves another what if out of the equation... Just use a heavy rated switch, and of course a good relay. Fuse to be rated........ Been doing this/working for all ride's for years,past and present.
     
  17. fordflambe
    Joined: Apr 9, 2007
    Posts: 398

    fordflambe
    Member

    Nothing wrong with manual control.

    However, i have to say you sound a little like my wife when setting the HVAC controller in our home. She likes to turn it on and off based on her comfort rather than allowing the T-stat do its job.........

    Actually, for a fan controller, you can have both. The temp switch (in your coolant passage) is just an input to to determine when fans (or controller) know when to come on. You can also wire a manual switch as an override (in parallel) so you can manually turn fan on.

    I know, I know, ..............lots of extra wiring when it can be done much simpler.........
     
    gimpyshotrods likes this.
  18. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,221

    atomickustom
    Member

    Actually this is my plan. I already have the switch and wire mostly in place from when the electric was a small auxiliary fan. Now I just need to pick up a good relay and temp switch and hook it all back up.
    The fancy controller is dead now - fan runs continuously on high no matter where the temp is adjusted or the car's temp.
    Sent from my SM-T350 using The H.A.M.B. mobile app
     

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