Cooling system

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Cooling system

Unread post by Guest » Sat Jun 27, 2020 11:39 am

I have a1997 Olds Cutlass supreme . I have installed 2 new fans , a new T stat,
also a temp. sending unit . The relays are making when bench testing and all fuses are good . Fans will not come on . ?

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Re: Cooling system

Unread post by carriedi » Sun Jun 28, 2020 6:53 pm

Is the check engine light on? Can you scan the PCM and watch the temp sensor reading? How hot does it get before it shows a fan signal going out? Do the fans come on when you turn on the AC?

If you have verified the operation of the two relays and they work normally, you need to check if they are getting a signal from the PCM. The PCM sends a ground signal to the relay to complete the electromagnetic circuit that should close the switch to power up the fans. The best way would be to connect a scanner and tell the fans to turn on and see what happens. Without a scanner it's harder. First, the temp has to go over 223F before there would be a fan request. That should be over 3/4 on the temp gauge.

here is a wiring diagram so you can follow where you have the problem with the signals
97 cut supreme fan. jpg
97 cut supreme fan.jpg

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