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Radiator fan wont shut off

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Old Mar 18, 2011 | 11:57 PM
  #1  
Tory Cook's Avatar
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From: Grand Haven, Michigan
Car: 1991 Camaro RS
Engine: 305 V8 5.0
Radiator fan wont shut off

hello, my problem has never happened before this spring. my car has been sitting over the winter and everything was working perfect until i drove for a while like an hour or so and then all of a sudden my radiator fan will not shut off. Even if i turn my car off and take key out of the ignition. My temp is around 140 degrees and it stays there i know its not that temp but it wont move. but when i start it up it will be at a lower temp but when i start driving it goes to 140-150 and flutters at times. any one have this problem or know of solutions. also the only way i can shut the fan off is to disconnect the battery.

Thanks in advance

Tory

Last edited by Tory Cook; Mar 19, 2011 at 12:01 AM.
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Old Mar 19, 2011 | 12:03 AM
  #2  
84redta's Avatar
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From: Stamford, New York
Car: 80 SE/TTA;88 T/A GTA;86 T/A
Engine: 4.9L Turbo; LT1; empty
Transmission: TH350; T56; empty
Axle/Gears: 3:23 disk; 4:10 disk ; 3.42 disk
Re: Radiator fan wont shut off

So does the fan stay on when the car is off? Or just when you start the car the fan turns on and stays on? The temps are normal to fluctuate as the fan comes on and off, at least on a TBI engine. Temps should be making it to 210 as far as I remember, been a while since i've been behind the wheel of my hibernating bird, but it's roughly just under half, and fluctuate to just above half till the fan brings it back to before half.
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Old Mar 19, 2011 | 09:08 AM
  #3  
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From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: Radiator fan wont shut off

For the gauge, try a new sender - driver side head, between #1 & #3 spark plug, has single dark green wire to it.

For the fan, unless someone has rigged it to run always, it won't run very long after key is off, but it will run for a minute or two sometimes after key is off. Might need a new fan switch, located pass side head between #6 & #8 spark plug, has single wire, mushroom-looking connector.
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Old Mar 19, 2011 | 11:41 AM
  #4  
Tory Cook's Avatar
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From: Grand Haven, Michigan
Car: 1991 Camaro RS
Engine: 305 V8 5.0
Re: Radiator fan wont shut off

I changed the fan relay switch in it and i tired it but it doesn't change anything. The fan does run after the car is off and key out of ignition for ever until my battery would die. i took the positive off so it wouldn't drain the battery. i unplugged the sensor on the front of the motor to test if it was that but it wasn't. does anyone know if it could be that it isn't grounded right? if so how to go about testing it?
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Old Mar 19, 2011 | 11:55 AM
  #5  
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From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: Radiator fan wont shut off

I'm lost - something weird is going on.

Remove the relay, then see if the fan runs at all. Turn on the A/C to make the fan run with key on, if it does, let us know. That means the relay is not being used in the system.
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Old Mar 19, 2011 | 11:58 AM
  #6  
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Car: 1989 Pontiac Firebird Trans-Am GTA
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Re: Radiator fan wont shut off

There should be a large bosch style relay either up front by the radiator or on the firewall I dont remember exactly, that controlls the main power to the fan. This relay can arc shut if its older when the fan is switched on. To check it pull out the relay and listen or feel for an internal click, if you dont here the relay click and the fan turns off you probably have a bad relay. Plug it back in and tap it with a pair of pliers or a screwdriver it may knock the contact loose. To check the relay you need a multimeter, and a 12v source. Put the coil terminals of the relays to 12v and meter the contact terminals. You should see them change state from open to shorted if the dont the relay is bad.
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Old Mar 19, 2011 | 12:25 PM
  #7  
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From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
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Axle/Gears: 3.42 posi
Re: Radiator fan wont shut off

He said he already replaced the relay. But - maybe he replaced the fuel pump relay and not the fan relay ... Fan relay has a large black with red stripe wire, fuel pump relay does not - that's how to tell the difference between the two.
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Old Mar 19, 2011 | 04:01 PM
  #8  
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From: Grand Haven, Michigan
Car: 1991 Camaro RS
Engine: 305 V8 5.0
Re: Radiator fan wont shut off



this is what i was told was the problem and i replaced the part and it didn't change a thing. this is located near my firewall.



the picture above is the other sensor i took out and tested to see if it would change anything but it still isnt. Once i put the positive back on the battery the fan starts.

also i removed the relay and tried the a/c and it wouldnt work when the key was on but when i plugged the relay in it worked fine. radiator fan still was running.


i think it has to do with the wires them selves in my opinion but what do you think?

Last edited by Tory Cook; Mar 19, 2011 at 04:17 PM.
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Old Mar 19, 2011 | 04:58 PM
  #9  
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From: Grand Haven, Michigan
Car: 1991 Camaro RS
Engine: 305 V8 5.0
Re: Radiator fan wont shut off

I tested the wire connected directly to the fan it self and it gave me a positive on both wires so one of the grounds is messed up:/
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Old Mar 19, 2011 | 05:22 PM
  #10  
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From: Central California
Car: 92 Camaro RS
Engine: LO3
Transmission: T5
Axle/Gears: stock
Re: Radiator fan wont shut off

It does sound like the relay may be fried and staying on. The fan relay looks just like the one in your pic, but is located on the driver side between the brake booster and the fender. There should be two of them behind a small metal frame that holds them. The fan relay has four wires going to it, the other one has five. That's the one to check/replace. The other sensor you show is the CTS and has no effect on the fan in your single fan system.
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Old Mar 20, 2011 | 01:45 PM
  #11  
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Car: 87 Formula/ 00 Xtreme
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Re: Radiator fan wont shut off

Originally Posted by camaronewbie
it won't run very long after key is off, but it will run for a minute or two sometimes after key is off.
It should not run at all with the key off. The coil side of the relay is powered by 'key on/run' only. It should not be powered during crank as well.
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Old May 29, 2011 | 06:40 PM
  #12  
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From: yonkers ny
Car: 84 T/A Recaro
Engine: L69 H.o
Re: Radiator fan wont shut off

Hello everybody

I have the same problem.
Today i was Cruising all day and when i got home i park the car turn off the engine and the radiator far is still running so now i have to disconnect the battery.

no idea what's the problem
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Old Mar 5, 2016 | 10:44 PM
  #13  
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Re: Radiator fan wont shut off

Having the exact same problem. cant get the damn fans to turn off. its hit or miss. was driving all day today, didnt start acting up till much later on. after the car had sat for awhile.
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Old Oct 14, 2020 | 08:53 AM
  #14  
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From: Katy, TX
Car: 1989 Camaro RS
Engine: 305 TBI V8
Re: Radiator fan wont shut off

Originally Posted by tiredgrunt0311
Having the exact same problem. cant get the damn fans to turn off. its hit or miss. was driving all day today, didnt start acting up till much later on. after the car had sat for awhile.
Did anyone ever solve this problem? I have the same issue with the fan running with the car off and the key out plus the SES stays lit with key on but has no codes besides 12. Any thoughts would be appreciated!
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Old Oct 14, 2020 | 09:27 AM
  #15  
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Re: Radiator fan wont shut off

It's the fan relay.

The guy from years ago probably changed out the wrong relay.

Look for the one whose connector has a red or orange (big), blk w/red stripe (big), pink w/ blk stripe (small), and grn w/ wht stripe (small). Replace it.
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