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NO FANS TURN ON

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HI IM NEW HERE ...I HAVE A PROBLEM WITH MINE I A HAVE A 1996 FIREBIRD FORMULA CONVERTIBLE THAT I DONT SEE OR HEAR THE FANS TURN ON 馃 ANY HELP!!
PLEASE
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What maximum temperature does the dash coolant gauge show? Fans don鈥檛 come on until temp reaches 226掳F.

Is the SES light on? There are codes for the fan relay circuits (signal side).

And the fans don鈥檛 come on when you turn the A/C on?
I did put a switch to the relay and they do turn on with the switch and when i disconnected the plug from the water pump censor they turn on or i dont know if the cylinder head censor is bad i just got a new one to install
Driver side cylinder head sensor just feeds the dash gauge. The coolant temp sensor in the bottom of the water pump housiing feeds the PCM, which controls the fans. Disconnecting the water pump sensor should turn on the SES light, as should failure of the circuit on the signal side of each relay.

So let's try this again:

WHAT IS THE MAXIMUM TEMP YOU HAVE SEEN ON THE DASH GAUGE? Or is it not working?

IS THE 鈥漇ES鈥 light on?

If you want help you have to answer ALL the questions.

Here's how to test the two coolant temp sensors - scroll down past the resistance chart:

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THE GAUGE GOES ALL THE WAY TO THE RED.
SO THERE IS TWO SENSORS FOR THE FANS
SO THERE IS TWO SENSORS FOR THE FANS
NO!

The coolant temp sensor in the bottom of the water pump housing feeds the PCM, which controls the fans.
But you also need to test the dash gauge sensor as well, because that may be giving you false readings on the dash gauge.


IS THE 鈥漇ES鈥 light on?

If you want help you have to answer ALL the questions.
Third (and last) request ! ! !
Yes the check engine is on. im going to scan for codes thank you for all the help ..im going to test the sensors
I did put a switch to the relay and they do turn on with the switch鈥
Is this a PERMANENTLY installed switch?

If you didn't follow this diagram:


鈥. that switch could be causing the SES light.
THANK U AND WHAT KIND OF SWITCH SHOULD I USE.IF U HAVE A PICTURE
Again, please answer my question - did you already permanently install a switch to control the fans? I'm trying to help you, but you won鈥檛 give me the info I need.

To clarify鈥. are you planning to install a switch to control the fans, rather than figure out why they aren鈥檛 turning on? Or is a switch you already installed possibly causing the problems?
I really want to fix the issue i dont want to run switches i wanted to run normal like it should i bought new sensors gm brand for the gauge and the water pump
U THINK THERE IS A SHORT SOMEWHERE
THANK U FOR AL THE HELP !!!!!
Then why were you asking me for a picture of a switch?

This makes no sense at all. I give up.
Thanks for all the help
馃う鈥嶁檪锔
Download the Factory Service Manual for your year from the link below and use Adobe Reader to keyword search through it. In it you will find the correct wiring diagram for your year along with the locations of all the harness connectors. With the wiring diagram and the circuit specific diagram already included in this thread, you should be able to follow the electricity through the circuit.


When you "switched" the circuit and the fans cam on, how did you do that? Did you apply power or ground to the relays? ...or something/somewhere else?

Also, there are actually codes for failure of the low and high speed cooling fan circuits. Does your Check Engine AND SES lights both illuminate during bulb-check when the key is first turned from OFF to RUN? If not, SCAN that PCM, you probably have a code waiting.

If the CE and SES bulbs illuminate during the bulb/system test, and manually switching the fans got them to run, it may just be possible you're not hitting the first temperature threshold for the fans to come on.

I live in West Central Florida, both my LT1's are running below fan temps so far. I drove around for an hour yesterday in my C4 and never exceeded 221F, so my fans never spun up. Completely normal!

Also, with the low/high speed setup you have, both fans come on low speed (half-voltage) and if needed switch to high speed (full-voltage). When the hood is closed, it's impossible to hear the fans on low, and if the hood is open, it's still extremely hard to hear them kick on. Even the switch to high-speed isn't too noticeable with the hood closed.

If the cooling system is performing as it should, high-speed fan activation is really uncommon unless it's extra nasty outside, or you turn on the A/C. Usually, low-speed is enough (even sitting idle) to bring temps down and cut the fans off.

Are you even overheating? If your temperature needle is going high but the engine isn't getting sluggish, it's more likely your temp gauge is getting bad readings from the sensor in the head. The temp gauge has absolutely nothing to do with fan operation, it's there for your eyes only. The PCM controls the fans based from a sensor on the water-pump.

Of course, there's the fact that even the slightest amount of air in an LT1's cooling system greatly impacts efficiency. Fans could be operating as designed, the system could be 100%, and a little air will in the system will affect it like there was no coolant at all. If you've never bled the cooling system, try it. If you have but suspect you didn't get all the air out, elevate the front end so that the bleed screws are the highest point and try again. Sometimes it's necessary to do that.

Good luck!
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I had and fixed the same/similar problem last week. Fans only came on when the A/C was running. Unplugged the electrical connector from the ECT sensor located on the water pump and the fans would kick in. Replaced the ECT sensor. Fans now come on when the temp gauge hits 126 as intended w/o having to the run the A/C.
I had and fixed the same/similar problem last week. Fans only came on when the A/C was running. Unplugged the electrical connector from the ECT sensor located on the water pump and the fans would kick in. Replaced the ECT sensor. Fans now come on when the temp gauge hits 126 as intended w/o having to the run the A/C.
Thank you for the reply im going to try that since i just got a oem sensor
If going after that sensor, make sure the car is cool. Even after draining the radiator, you're still gonna have some coolant coming out of the hole where you pull the ECT sensor. No need to get blasted with scalding hot coolant
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