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  1. #1
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    Question 5.7 cooling fan comes on high very quickly

    I've noticed recently as the outside temps are in the 90's, that the cooling fan always seems to come on high speed (very loud), soon after starting the car (like within a min or two.) I don't recall it doing this last year at all. I can hear it inside the house! I could see this if the engine was hot and sitting idling, but this is within a minute or two of starting cold daily in these hot ambient air temps (90+).
    Coolant is full and clean. No warning lights of any kind.
    Any ideas?
    Thanks!



  2. #2
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    Either :


    A/c is requesting the high fan due to high temps



    Or your low speed fan motor/relay is bad and the car defaults to high on to protects itself.
    2011 Dodge Charger Pursuit 113K Miles. Stock for Now.
    Cop Brakes, Cop Exhaust, Cop Suspension,
    It's the model with the big bull bar so pedestrians get out of the way.


  3. #3
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    Even if you are a single fan setup, you should have three fan relays in the front power distribution center.
    I assume you have a single fan,

    On a dual fan setup relay 1 runs both fans on low speed, when high speed is called for Relay 1 drops out and Fan Relays 2 & 3 run each fan on high speed.
    I'm not sure if a single fan setup lets one of the 2 & 3 relays go un-used or not. I know the swap to dual fans with an OE set was plug and play, no flashing, nothing, just swap and plug em in.

    If you are a single fan and have all three relays in place, try swapping one of the Rad Fan 2 or 3 relays with the Rad Fan 1.
    (Use a marker or something to ID the relays you are moving around or you can loose track playing the shell game)

    While its running on high pull 2 or 3 to see which one its running on high with. Then take the one its not using and swap it with #1 and see if that will get your low speed back.

    I just went through this with a dual fan setup where a motor was going bad and locking up after running a while and finally seized. It overheated its relay.

    I got a temp BWD brand relay from Advance Auto until I got some MOPAR replacements. 4727370AA
    BWD
    Electrical Relay
    Part No. R4826



  4. #4
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    Duplicate, Mods please delete?

  5. #5
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    I'll check out the relays, thanks for a direction to go in.

  6. #6
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    Quote Originally Posted by gapi View Post
    Even if you are a single fan setup, you should have three fan relays in the front power distribution center.
    I assume you have a single fan,

    On a dual fan setup relay 1 runs both fans on low speed, when high speed is called for Relay 1 drops out and Fan Relays 2 & 3 run each fan on high speed.
    I'm not sure if a single fan setup lets one of the 2 & 3 relays go un-used or not. I know the swap to dual fans with an OE set was plug and play, no flashing, nothing, just swap and plug em in.

    If you are a single fan and have all three relays in place, try swapping one of the Rad Fan 2 or 3 relays with the Rad Fan 1.
    (Use a marker or something to ID the relays you are moving around or you can loose track playing the shell game)

    While its running on high pull 2 or 3 to see which one its running on high with. Then take the one its not using and swap it with #1 and see if that will get your low speed back.

    I just went through this with a dual fan setup where a motor was going bad and locking up after running a while and finally seized. It overheated its relay.

    I got a temp BWD brand relay from Advance Auto until I got some MOPAR replacements. 4727370AA
    BWD
    Electrical Relay
    Part No. R4826

    I keep forgetting Reg LD bodies got single fan setup.

  7. #7
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    I checked out the 3 relays/1 fan and even swapped them around to see if it made any difference today and it didn't (though I did find out it sets a code if you pull one when its running, oops ) It does seem to be the AC is making it comes on high. Perhaps I just didn't notice it last year as I was working nights mainly then so maybe didn't use the AC as much?! Though I don't know how I could miss this noise as I can hear it inside even! Temps seem fine/stable at 200*F and the most I saw it sitting there after running it idling in one spot for an hour was 214*F (120-135* IATs).

    No codes or anything.
    Anything else I should check?

    Think I should pop in a slightly cooler thermostat (190 maybe - would I need a tune?)?

    gapi, I want your car so bad (or at least the SC) lol
    Last edited by IcarusLSC; 07-28-2020 at 07:45 PM.

  8. #8
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    You have several parameters that interact with the fan including AC pressures and Trans Temps.
    My car seed strange but welcomed that when a motor failed to run on low together with the other it ran the other on high.

    Maybe you are OK.

  9. #9
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    Give you an idea, My 2011 Pursuit has dual fans. Today while idling in a parking lot with 93* showing. With my a/c on the fans were on high Alot if not nearly continuous.

    But boy was my A/c just fantastically chilly.

  10. #10
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    Yes, my AC works great too. I guess this is the way its supposed to be...
    Thanks all for the help and info

    Anyone think running a slightly cooler TStat would help any (like a 190*)?

  11. #11
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    Quote Originally Posted by IcarusLSC View Post
    Yes, my AC works great too. I guess this is the way its supposed to be...
    Thanks all for the help and info

    Anyone think running a slightly cooler TStat would help any (like a 190*)?
    Personally on a stock vehicle. No. I never bought into the lower T-stat temp stuff.

    I bought into the help the system shed heat better way of thinking. Which si why I like the Pursuit with its upgrades, even then I added a SRT thicker core radiator in to help it out and it did a lot.

    With stock T-stat, I will run low 190s on highway, and stay in the mid to low 200s. Like today idling with fans on with 93* outside it stayed at 201* steady til I started moving and it dropped more.

    I did however change my fan settings. My low speed fan now kicks on at 208* (stock was 217*) and high 217* (stock was 225).

  12. #12
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    Quote Originally Posted by IcarusLSC View Post
    Yes, my AC works great too. I guess this is the way its supposed to be...
    Thanks all for the help and info

    Anyone think running a slightly cooler TStat would help any (like a 190*)?
    If you change to a lower thermostat, the fans will still come on/off/high speed/low speed at same temp due to they are programmed around the original original thermostat temp. You will need a programmer to change the temps for fan speeds.
    I run a 180 Tstat and my fan settings in my Predator are set at 180/190. Originally they were up over 200. My car rarely is over 190, most of time at 185.
    Last edited by netnathan; 07-29-2020 at 05:43 PM.
    Net is where I be......Nathan is me
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  13. #13
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    Quote Originally Posted by IcarusLSC View Post
    Yes, my AC works great too. I guess this is the way its supposed to be...
    Thanks all for the help and info

    Anyone think running a slightly cooler TStat would help any (like a 190*)?
    I've put a 180 in mine (06 Magnum) and adjusted the fans down. I live in Phoenix, so it's a million degrees outside. After getting off the freeway after about 5 or 10 miles, the temp is around 195 or 200. Driving the streets it stays around 190. I did adjust the fans down though, I think the low kicks in at 190 and the high at 200.

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  14. #14
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    A fully open 203°F thermostat is letting the same amount of coolant flow as a fully opened 180°F. So what ever benefits there are, or are not, equalize after a time when they are open fully.

    That said, my tuners prerequisites are to install 180°F thermostats and bring the car.
    I don't argue or ask for an explanation. All I know is going from single fan thin radiator to dual fan thicker radiator is my temps recover faster after romping around.

    Going too cool in less severe weather can keep the car in warmup mode and burn extra fuel.

  15. #15
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    Another way to think of a thermostat is when fully warmed up a 180°F thermostat will not allow coolant temps lower than 180.
    I took a couple screen shots today. Holding the temp up and down along with the rear defrost for a screen shot while navigation was fun.

    85mph Cruise for 20 miles.





    In line at Starbucks after a little romping on I75 and pulling off for a cup. The oil temp was @214 but dropped
    quickly after the romping.



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