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after market electric fan relay kit

 
Old 03-11-2019, 03:13 PM
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bud40oz
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Default after market electric fan relay kit

my fans seem to be all messed up, due to the fire it had i am sure plus with the previous owner removing the factory tuned port system and me not knowing what all they hacked up for wiring, i think it would be my best choice to just look at the aftermarket fan relay kits. i see summit has some for dual fans with a new temp sending unit and everything for 100 bucks or so. if i am re-wiring it basically, it will eliminate the need for ecm controlled fan. pretty much how this car is headed anyways. it no longer has fuel injection and really is no longer even an l98 engine without it i suppose. should i just wire up both fans to come on and off together on a dual kit. that's what i think i should do, i know the one fan is supposed to be for when the ac unit engages but what would it matter if they both just ran together, also what would be the best temp range for the on/ off points when i buy a kit. i'm thinking 200 on, 185-190 off, maybe some one knows of a good quality brand kit and model number for me to start looking at, any help is always appreciated as usual
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Old 03-11-2019, 08:16 PM
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Hot Rod Roy
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How would you like the fans to operate? You could have one fan that turns on when the a/c is turned on, and the other fan turn on when the engine temp exceeds your chosen temperature. This would be a simple configuration, and would not depend on the ECM.

I don't have the wiring info for a '91. Is there a temp sensor in the LH head, between plugs 1 & 3? You could use this location for a CTS (coolant temp switch) to operate a relay for the main fan. You could wire the a/c low pressure switch to a relay to operate the secondary fan, so it would turn on any time your a/c is on. Let me know if you'd like to see a wiring diagram of this idea.

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Old 03-11-2019, 09:49 PM
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bud40oz
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that is pretty much how it's designed from factory so it would work for sure, how ever the car is a convertible, plus i am not really an a/c kind of guy i enjoy windows down and air flowing personally. though i do enjoy a hot summer night with ac on AND windows down. and also, no i did not see a sensor in the left side head i saw one between 6 and 8 is all i found. i looked the other day because i have been reading old posts about this here.. but i did not see anything on the drivers side at all, i will look again next time we get a warm day and i pull it out of the garage
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Old 03-11-2019, 09:52 PM
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bud40oz
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i guess i was thinking since from everything i read here, these cars tend to run really hot. much more than anything i have ever known to be good. sure i know a long time ago they figured out that these engines run best at like 210.. but 240? that's crazy hot 260 and i would shut it down from fear of damaging the engine. that's why i had the dual fan at once in mind i guess

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Old 03-12-2019, 01:27 AM
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Originally Posted by ihatebarkingdogs View Post
You do NOT want the fans to run at road speed, as they will restrict air-flow.
Sorry, IHBD, but this doesn't make sense to me. How would running the fans restrict air flow? Even if the fans have no power applied, they will be spinning at road speed, because of the air flow.

I think the OP is trying to not use the questionable ECM on his butchered car.

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Old 03-12-2019, 01:10 PM
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the thought of my engine running at 220-230 just makes me cringe, i don't think i will be able to force myself to allow any engine of mine to run that hot
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Old 03-12-2019, 03:47 PM
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IHBD, your explanation makes sense. Thank you. I hadn't thought of that! That also explains why I have never seen the radiator fan in my '84 turn on at speed . . . because the air flow thru the radiator at speed is higher than it would otherwise be with the fan running! So it appears the later model ECM control to de-activate the fan at speed is superfluous. My engine runs at about 200 deg, and the fan does not operate at speed. At idle, the fan cycles on and off. (I have an LED indicator on my radiator fan circuit.)

Does the later 'vette ECM de-activate the secondary fan when the a/c is on at speed? If not, it seems that activating the a/c at speed, and therefor running the secondary fan, would cause the engine to run HOTTER! (?) I haven't noticed that problem when the a/c is activated on my '84 (my fan control is not so intelligent!).

Bud40oz, what would you like to do? My circuit would use one CTS (not two), two relays (not three), and no switches. The CTS would mount in your LH head, between plugs 1 & 3. The fans would be independently controlled. It's your call.

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Old 03-12-2019, 09:01 PM
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Do you current fans work? I bought one of the kits from somewhere, Ecklers maybe, which turns on the fans at a certain temp and they work great. The ECM will still turn it on for AC or when you put it in diagnostic mode.
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