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replaced fan sensor now temp reads hot

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Old 10-14-2018, 12:17 PM
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Car: 1991 base firebird
Engine: tbi 305
Transmission: 700r4
replaced fan sensor now temp reads hot

fan sensor switch broke. I bought a replacement but when I pulled the original out of the block they didn't match. the new one was a bit longer. I had it out and decided to try it. there is a hard line that runs near the sensor location and the extra length of the sensor made it almost impossible to get to because of the hard line interference. got it screwed in far enough that its not leaking but there are a lot of threads still showing. not nearly as close tot he block as the original. started car and the temp gauge immediately read 220. the motor was still cool to the touch but it read 220. anyone know what might cause this? im taking the original back to the parts store to make sure its identical.
Old 10-14-2018, 12:20 PM
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Re: replaced fan sensor now temp reads hot

Did you bleed the cooling system after you installed the switch ?
Old 10-14-2018, 12:24 PM
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Re: replaced fan sensor now temp reads hot

Post #20 the sw555 is a good replacement choice
https://www.thirdgen.org/forums/cool...an-switch.html
Old 10-14-2018, 07:41 PM
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Car: 1991 base firebird
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Transmission: 700r4
Re: replaced fan sensor now temp reads hot

"tuned performance" I didn't bleed the system but I didn't think it would cause this. I mean the gauge shot to 220 at start up. however today the temp gauge seems to be working fine so maybe it was an air bubble in the system. the fan still isn't working but as long as I have the a/c on to run the fan cars great. so at least I don't have to park it while I deal with this. I will look at the link you posted. I just came from orileys with the original sensor and they coulnt find it in their system. the only one they pulled up was longer and interferes with that hard line.
Old 10-14-2018, 08:23 PM
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Car: 1991 base firebird
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Transmission: 700r4
Re: replaced fan sensor now temp reads hot

this is the switch I pulled out of the car.

Old 10-14-2018, 08:25 PM
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Car: 1991 base firebird
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Transmission: 700r4
Re: replaced fan sensor now temp reads hot

I like the idea of the v6 switch tuning the fn on around 210 but it also looks longer than this one. I may also look into replacing the plug as well. if the tip of the sensor has deteriorated to the point it crumbled maybe the plug is doing the same. the 606000 switch looks good and comes with a plug but im not stoked to spent $50 on a fan sensor. however I would rather spend $50 now to fix it correctly than $$$ down the road when I overheat it and destroy the motor.

Last edited by Evilokc; 10-15-2018 at 07:43 AM.
Old 10-15-2018, 02:44 PM
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Re: replaced fan sensor now temp reads hot

Are you sure you replaced the temp sender not the fan switch?

If you are maybe you got a bad one
Old 10-15-2018, 08:14 PM
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Car: 1991 base firebird
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Re: replaced fan sensor now temp reads hot

Originally Posted by midias
Are you sure you replaced the temp sender not the fan switch?

If you are maybe you got a bad one
nope. im not sure. the pic shows the sensor that's broken and the fan isn't working so I "THINK" I have the fan switch out. the round end where the pigtail plugs into is what crumbled and fell off. I lost my chilton manual so I couldn't verify it that way. I bought another but it hasn't come yet.

Last edited by Evilokc; 10-15-2018 at 08:18 PM.
Old 10-15-2018, 08:38 PM
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Re: replaced fan sensor now temp reads hot

I am not sure what type of car you have and this might vary from year to year but your fan switch should look like this






And you gauge sender should look like this




Eitherway rockauto has you covered. I prefer the 89 turbo V6 trans am fan switch 210 on
Old 10-15-2018, 09:00 PM
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Re: replaced fan sensor now temp reads hot

If your replacing the passengers side that’s correct one for the fan.
https://www.thirdgen.org/forums/elec...hats-plug.html
Old 10-16-2018, 10:22 AM
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Re: replaced fan sensor now temp reads hot

Obviously you swapped the wrong sending unit - you swapped the one for the gauge and not the fan switch.

GD
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