Wiring LS1 Fans into 2nd Gen

Discussion in 'High Tech Retrofits' started by Steve's 74, Feb 24, 2006.

  1. Steve's 74

    Steve's 74 Veteran Member Lifetime Gold Member

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    New project on the 74. Electric Fans. Need as much help as possible with electronics, so........

    Lots of questions;
    Should I go with a variable controller that increases fan speed as temp increases?
    Are 30amp relays the correct size for these fans. What's the initial max draw off of each fan?
    Will 1 fan provide enough cooling?...Could I run them as 2 seperate units, 1 for normal cooling on at 180 and 1 to come on as needed at higher temps (200). 2 reasons...less initial amp draw and in case I blow a fuse (fuseable link?) I still have a fan to do some cooling.
    Or is it better to have them come on together and just protect them individually?
    Best place for temp sensor in radiator? bottom pass side (after cooling) or top driver side (before cooling).
    Suggeted mounting location of controller/relays?
    Energize through BAT, IGN, or ACC ?
    Vendors for quality custom made wires?
    Opinions on wiring and products wanted.

    Steve
     
  2. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

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    Good question......I just got my LS1 fans yesterday.
    No idea where i'm supposed to plug the relays into though.
     
  3. schitzo

    schitzo Veteran Member

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    I can answer some of your questions
    a 30 amp relay for each fan is enough.
    I would suggest wiring it so that the second fan somes on when needed.

    To control the fans, you can use some sought of adjustable mechanical thermostat fan control. It will provide the ground for the fans when needed. Check out Hayden part #3653. Performance Automotive warehouse should have it.

    You want to place the plobe at a place where it can read the temp of cooled coolant. That way if the coolant needs further cooling, the fan speed can be increased or the second fan turned on.

    I would not recommend having the fans come on at the same time. It is not neccessary and the intinial amp draw might cause some damage somewhere.

    Wire your setup through the IGN ON/OFF source so that the fans can only come on when the car is running. Wiring through a constant live source might have the fans running after you turn the car off.

    As far as mounting is concerned, I chose to have my relays as close to the fans as possible that way the wire providing the power to the fans was as short as possible. Here is a pic of the fans and headlight relays.
    [​IMG]
     
  4. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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  5. Steve's 74

    Steve's 74 Veteran Member Lifetime Gold Member

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    Yea, I was looking at those from your other post. The FK-60? "Our complete fan controller kit (FK-60) utilizes the variable output controller, low mass temperature probe and wiring loom to provide closed loop variable speed control of virtually any automotive cooling fan (up to 60 Amps continuous)."
    Hard for me to tell from the description and wiring diagrams they show, but it appears this unit would include a single 60amp relay and activate both fans simultaneously. I don't think that's what I want to do. I could go with 2 FK-35 kits and each fan would be independent, leave one at 180, then change the jumpers on the second to kick in at 202.

    Thanks for all the info. Actually, I was thinking I might want to pull of the ACC so I could switch the fan on after shutting the car off. After looking at the FK-35 a bit more, it seems it does provide a bit of run after the car is shutdown. Not sure, here's what it says, "Auxiliary wiring-Ignition input:
    The control unit will shut itself off automatically soon after the engine is turned off. If an Immediate shut off is required, connect the yellow ignition input wire of the harness to the unit and to any source that is higher than 6 V whenever the ignition is on. "
     
    Last edited: Feb 24, 2006
  6. Steve's 74

    Steve's 74 Veteran Member Lifetime Gold Member

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    schitzo, trying to find some info on the Hayden part #3653. This will only control input (on/off, not fan speed), right?
    So are your fans always on full speed?
     
    Last edited: Feb 24, 2006
  7. schitzo

    schitzo Veteran Member

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    I am installing a Ls1 so my fans are going to be controlled by the ECM. it does not vey the speed ( I think)....I just turns on the second fan if need be.

    There are numerous fan control modules out there. Do a search and you should be able to find exactly what you need.
     
  8. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    Here are some diagrams I have come across (click most to enlarge). Where applicable, replace ecm connectors with varying temperature fan switches (one higher temp than the other). You would have to add a link to turn them on high for AC (ECM probably does that too). You can also splice in a manual override if you wanted to.

    Two Fans, 1 on at lower temp, other comes on at higher temp:
    GM LT1 early: [​IMG]

    Two fans, both at 6 volts at lower temp, full 12 with higher temp switch trips:
    GM LT1 later: [​IMG] Version from LS1tech: [​IMG]

    Here is a basic fan setup. For two fans, I would add another relay. I'd draw it, but I am not in the mood. :crazy:

    [​IMG]


    IMO, the version above that runs both fans at slow voltage, then at higher, would be best. However, given the price of 3 relays & two fan switches, the dcc controller is a better way to go.
     
    Last edited: Oct 30, 2006
  9. Steve's 74

    Steve's 74 Veteran Member Lifetime Gold Member

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    Thanks for the diagrams. You're obviously ahead of me. Looks like the DCC would be the right choice, and the jumpers are a nice feature. Why try to re-invent.
    Stupid note to self... what good is leaving the fans on after shutdown if there's no active electric water pump to move it through the engine. duh!
     
  10. Steve's 74

    Steve's 74 Veteran Member Lifetime Gold Member

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    Individual LS1 fan load?

    Anyone know the actual load that each fan draws, initially and when running fulltime? I've also thrown up a post for this on LS1Tech.
     

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