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Coolant temp sensor and coolant temp switch/fan switch

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Old 03-06-2011, 07:53 PM   #1  
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Coolant temp sensor and coolant temp switch/fan switch

The coolant temp sensor is right by the thermostat, right? Where is the coolant temp switch/fan switch?
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Old 03-06-2011, 07:59 PM   #2  
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Re: Coolant temp sensor and coolant temp switch/fan switch

driver side head, right behind the AC compressor
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Old 03-06-2011, 08:06 PM   #3  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Nope - not there - at least not on V8.

Coolant Temp SENSOR (for the computer) - thermostat location
Coolant Temp SENDER (for the gauge) - driver head between #1 & #3 spark plug
Fan Switch - pass side head between #6 & #8 spark plug
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Old 03-06-2011, 08:24 PM   #4  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Cool. Thanks. :-)
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Old 03-06-2011, 08:44 PM   #5  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Now - if you have dual fans, only the secondary fan is controlled by the fan switch, the primary fan is controlled by the ECM. So, if you are having primary fan issues, might be bad fan relay. If having secondary fan issues, might be bad relay for that fan or the fan switch.

Oh - secondary fan should also come on with A/C - so if you have A/C still in tact and pressurized, start car when cold (so you know the ECM won't turn on the primary fan) , turn on A/C, and see which fan runs with A/C on - then you know which is which.
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Old 03-06-2011, 08:47 PM   #6  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Its a big single fan (14 inch).
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Old 03-12-2011, 07:56 AM   #7  
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Re: Coolant temp sensor and coolant temp switch/fan switch

How the heck do yo get to the Fan switch on the 305, from underneath? I hope not....I am a big guy and to get the car off the ground would be a chore.
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Old 03-12-2011, 10:13 AM   #8  
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Re: Coolant temp sensor and coolant temp switch/fan switch

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Originally Posted by Cwaterboy1 View Post
How the heck do yo get to the Fan switch on the 305, from underneath? I hope not....I am a big guy and to get the car off the ground would be a chore.
you can get to it from underneath and you can also fit a wrench between the primary pipes of your headers. You do have headers don't you?

If not, underneath you go
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Old 03-12-2011, 10:58 AM   #9  
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Re: Coolant temp sensor and coolant temp switch/fan switch

I do not have headers......so underneath I go. Or just take it the nearest shop and have them lift it up and do it. I hate paying for the labor when I can do it. Just getting underneath will be a chore.

I did check the fan and it does not come on when the temperature rises but does come on when I run the AC. Right now my AC doesn't work so I never run it. Am I replacing the right part?
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Old 03-12-2011, 12:49 PM   #10  
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Re: Coolant temp sensor and coolant temp switch/fan switch

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Originally Posted by camaronewbie View Post
Now - if you have dual fans, only the secondary fan is controlled by the fan switch, the primary fan is controlled by the ECM. So, if you are having primary fan issues, might be bad fan relay. If having secondary fan issues, might be bad relay for that fan or the fan switch.

Oh - secondary fan should also come on with A/C - so if you have A/C still in tact and pressurized, start car when cold (so you know the ECM won't turn on the primary fan) , turn on A/C, and see which fan runs with A/C on - then you know which is which.
I have dual fans and when my car gets hot the fan on the right- drivers side will go on but the one on the left passenger side NEVER comes on??? Is that considered the secondary fan thats controlled by the switch?
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Old 03-12-2011, 01:11 PM   #11  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Found that the pigtail with the plastic connector to the switch was missing so the wire was just hanging there. Connected a new pigtail from Oreilys $10.00 and all is good with overheating.
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Old 03-13-2011, 02:03 PM   #12  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Does anyone here know what temperature the fan switch should be activating the fan at?
My car runs cool on the freeway but warms up to around 220 and a little higher in stop and go traffic and the fan doesn't seem to come on until over 220.

I have called all the local auto parts stores and they have the fan switch in stock but they can't tell me what temperatures it works on.

When can I find one that will turn the fan on sooner?
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Old 03-13-2011, 05:06 PM   #13  
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Re: Coolant temp sensor and coolant temp switch/fan switch

220 is normal operating temp for these cars. Alternative switch part numbers can be found by searching "fan switch" and look for a thread that reads alternatives in the title.
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Old 03-13-2011, 07:44 PM   #14  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Got it "Camaronewbie"!
Neihoff DR137x is the cooler fan switch and turns on at 204 degrees.
The only problem is none of the local auto parts stores can get it!

Also my car has the 305 TBI v8 with single electric fan,where is the fan switch located on the single fan cars?
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Old 03-13-2011, 07:46 PM   #15  
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Re: Coolant temp sensor and coolant temp switch/fan switch

heres my dillemma, 87 iroc 5.7 tpi wire is there for the secondary fan for the fan switch...problem is i believe someone put a plug in the head where the switch was.....should i just take plug out and put switch there?
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Old 03-13-2011, 08:50 PM   #16  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Quote:
Originally Posted by JimRockford View Post
Got it "Camaronewbie"!
Neihoff DR137x is the cooler fan switch and turns on at 204 degrees.
The only problem is none of the local auto parts stores can get it!

Also my car has the 305 TBI v8 with single electric fan,where is the fan switch located on the single fan cars?

Fan switch is in the head between the #6 and #8 spark plug
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Old 03-13-2011, 08:54 PM   #17  
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Re: Coolant temp sensor and coolant temp switch/fan switch

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Originally Posted by JimRockford View Post
Does anyone here know what temperature the fan switch should be activating the fan at?
My car runs cool on the freeway but warms up to around 220 and a little higher in stop and go traffic and the fan doesn't seem to come on until over 220.

I have called all the local auto parts stores and they have the fan switch in stock but they can't tell me what temperatures it works on.

When can I find one that will turn the fan on sooner?
Read this stuff
https://www.thirdgen.org/forums/cool...ernatives.html
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Old 07-13-2013, 04:12 PM   #18  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Does anyone know where the fan switch is on my 92 firebird v6.
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Old 11-15-2013, 05:39 PM   #19  
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Re: Coolant temp sensor and coolant temp switch/fan switch

im intereted in knowing about the v6 too
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Old 03-22-2015, 07:18 AM   #20  
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Re: Coolant temp sensor and coolant temp switch/fan switch

on the v6- passenger side head rear buried by wire harness has a funny snout type connector
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Old 03-30-2015, 03:30 PM   #21  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Looking for advice. I have a 91 Firebird 305 tbi. It has been hard to start for years. The culprit wound up being a bad coolant temp sensor (next to thermostat). The guy at the parts store told me to wrench it all the way into the hole. Several other people have said that it is not supposed to go all the way in. I am hoping that I haven't damaged the intake. Any thoughts/opinions on this?
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Old 05-06-2015, 10:42 PM   #22  
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Re: Coolant temp sensor and coolant temp switch/fan switch

OK we now that i know where to find the sensors and which ones do what. Do any of you all know how a person would go about testing them with a voltmeter? I know im not into blowing cash on parts that are not needed. Id rather be buying ones that are needed.
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Old 05-11-2015, 09:53 PM   #23  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Does my AC have to be charged for the secondary fan to build enough pressure to spin? AC works just blows warm
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Old 06-25-2018, 05:08 PM   #24  
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Re: Coolant temp sensor and coolant temp switch/fan switch

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Originally Posted by camaronewbie View Post
Nope - not there - at least not on V8.

Coolant Temp SENSOR (for the computer) - thermostat location
Coolant Temp SENDER (for the gauge) - driver head between #1 & #3 spark plug
Fan Switch - pass side head between #6 & #8 spark plug
If your temperature sending unit in the driver's side head isn't working will that throw the motor off and cause slight back firing at loss of power
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Old 06-25-2018, 05:10 PM   #25  
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Re: Coolant temp sensor and coolant temp switch/fan switch

Dead thread, on a v8 the drivers side sensor is for the temperature gauge.
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Old 07-12-2018, 04:29 AM   #26  
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Re: Coolant temp sensor and coolant temp switch/fan switch

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Originally Posted by Cwaterboy1 View Post
Found that the pigtail with the plastic connector to the switch was missing so the wire was just hanging there. Connected a new pigtail from Oreilys $10.00 and all is good with overheating.
Do you have a part number for this? I think mine might have melted and is therefore shot. Thanks!
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Old 07-12-2018, 06:29 AM   #27  
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Re: Coolant temp sensor and coolant temp switch/fan switch

That post was from 7 years ago.

http://lmgtfy.com/?q=gm+fan+switch+pigtail Go ahead, you're smart, you can DO THIS.
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