cooling fan is not working, when should the cooling fan turn on?

1998 CADILLAC DEVILLE

CARRO

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I Think the cooling fan is not working, when should the cooling fan turn on? does it turn on at a certain temperature? Because i drove it one day and the temperature of coolant stayed around 197, but when i got home, i let it run for a little, and the temperature started rising just past 210, (i turned car off) and I looked to see if fan was on, but it was not on.

Jun 5, 2010 at 7:02 PM

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SQM

AUTOMOTIVE REPAIR CONTRIBUTOR
6,383 POSTS

Hello,

The cooling fan comes on when the engine reaches the operating temperature. It comes on and keeps the engine at the correct temperature and shuts off. The fan only works when the ECM sends the signal to the fan for it to operate.
This vehicle's operating temperature is 188 F - 206 F. So, it is possible that the temperature was within specification and the ECM did not send signal to the fan to turn it on.

The ECM gets the signal from the coolant temperature sensor. So, if that sensor sends incorrect data to the ECM the fan will not get triggered.

https://www.2carpros.com/articles/how-a-coolant-temperature-sensor-works

Observe the fan for the next few days and keep an eye on the temperature gauge. If it spikes, then there is an issue. If it stays within the operating temperature the fan does not necessarily need to come on.

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

Images (Click to enlarge)

Dec 18, 2021 at 6:49 PM