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VR V8 Thermo Fan Suggestions

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by Dean1985, May 18, 2020 at 8:14 AM.

  1. May 18, 2020 at 8:14 AM #1
    Dean1985

    Dean1985 Member

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    Hi all,

    I have done some world wide web digging but havent really found the specific answer im after.

    Car: VR S2 5L 1994.

    I recently completed a cam upgrade to a crane 284 and will be getting a tune done before it becomes daily driven.

    Currently i have an FG big single fan which seems to work amazingly.
    The AC condensor fan has been removed.
    At current the single thermo isnt properly wired in as i have some questions which will determine my way forward.

    I understand that its possible to control the fan circuit via the ecu. I understand that the ecu can have the temps set to control the fan on-off temps.
    I understand that the same circuit also comes on when you flick the AC switch.

    This begs 2 questions.

    1. What temp should the fan come on and go off at? Currently running a 92c thermostat.
    2. Can the ecu be configured to not flick this circuit on when the AC button is pressed (i dont really want the fan running constantly when the AC is on).

    *im thinking of still running my own elec circuit and just using the ecu signal to swifch my relay as the fan draws 35amps at startup and 22 during operation. The standard fan wiring is 15 amp.

    Any clues or links would be appreciated

    Cheers in advance
     
    Dean1985, May 18, 2020 at 8:14 AM
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  2. May 18, 2020 at 8:56 AM #2
    EYY

    EYY Well-Known Member

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    EYY, May 18, 2020 at 8:56 AM
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  3. May 18, 2020 at 9:15 AM #3
    Dean1985

    Dean1985 Member

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    So the big engine fan on at all times when AC is on?

    I have 30amp running to the Fan. Was thinking of using the signal wire from ecm to my own relay/fuse setup to allow for the extra amps (whammies) required by the fan instead of diggin into the harness to replace the two lots of wires that come from the relay box.

    Any idea on temp settings?
     
    Dean1985, May 18, 2020 at 9:15 AM
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  4. May 18, 2020 at 10:27 AM #4
    EYY

    EYY Well-Known Member

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    All my info is in that thread.

    A/C condenser fan isn't generally on all the time with the A/C running (if you have climate control). In any case, you definitely want it running whenever the A/C is running. Otherwise it's too hard for your cooling system to catch up when you get temp spikes in hotter weather. For A/C performance you want it running at high speed too. You won't even know its on when you're cruising.

    50A fuses blow with the single thermo setup over long periods of time. A decent 60a fuse is required along with 60a relay and wiring. Remember that current draw increases as voltage decreases. 30a fuse will work during testing but not in the real world as a daily driver with A/C still operational.

    You don't want your fan off temp at or below thermostat temp. With your current setup I'd go on at 98 and off at 94. Personally I'd go an 88* thermostat and have on/off set to 95/91 or thereabouts.
     
    Last edited: May 18, 2020 at 12:49 PM
    EYY, May 18, 2020 at 10:27 AM
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  5. May 18, 2020 at 11:41 AM #5
    Dean1985

    Dean1985 Member

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    Amazing reply Eyy. Thank you heapsssss!

    I will go 60 relay, fuse and cable. I will tack in to the acc power and the ecu signal wire which i believe goes to ground when the ecu flicks its switch.

    I did some tests by brudging pin 5 and 6 on the obd2 plug and turning the ignition on. In this condition it turns the engine fan on as diag mode.

    I have read your thermo thread a couple of times. Its what inspired me to piss off the twin fans and go a big single. It does indeed pull more air, less noise and sustain the temp amazingly (during run-in).
     
    Dean1985, May 18, 2020 at 11:41 AM
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  6. May 19, 2020 at 7:37 AM #6
    Dean1985

    Dean1985 Member

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    Hey mate. With regards to 60amp wiring etc.

    The wiring on the single thermo is like 15-20amp stuff (factory).
    The guy at supercheap looked at me weird last night when i asked where the 60amp wire was for a thermo fan.
    They didnt have 60amp relays and the 60amp fuses looked like novelty sized ines they use in TAFE class so people up the back can see them.

    How has your setup gone with all this since its been 12 months?
     
    Dean1985, May 19, 2020 at 7:37 AM
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  7. May 19, 2020 at 11:15 AM #7
    Lex

    Lex Well-Known Member

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    Go to a auto electrician. He will supply everything you will need.
     
    Lex, May 19, 2020 at 11:15 AM
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  8. May 19, 2020 at 11:26 AM #8
    losh1971

    losh1971 Well-Known Member

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    Jaycar will also have what you need. Autobarn also have some of this gear as they deal with car audio that uses heavy cable and fuses.
     
    losh1971, May 19, 2020 at 11:26 AM
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  9. May 19, 2020 at 11:55 AM #9
    EYY

    EYY Well-Known Member

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    Jaycar for the relay (they call it a horn relay) - can get wiring in packs from Supercheap (the 100a Narva stuff but it only comes in 5m) or by the meter from Jaycar. Relay base from online. My shopping list is in post 2 of that thread.
     
    EYY, May 19, 2020 at 11:55 AM
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  10. May 19, 2020 at 12:14 PM #10
    EYY

    EYY Well-Known Member

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    I used a maxi blade fuse when I did the conversion with the hj.
     
    EYY, May 19, 2020 at 12:14 PM
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  11. May 19, 2020 at 12:29 PM #11
    losh1971

    losh1971 Well-Known Member

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    You can go circuit breakers if you want it really tidy. That way you don't have lumpy cable joins from soldering in the maxi blade fuse holders.
     
    losh1971, May 19, 2020 at 12:29 PM
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