Cooling fans do not turn on

NOTAPROMIKE2

MEMBER
2002 PONTIAC BONNEVILLE
3.8L
V6
2WD
AUTOMATIC
140,000 MILES

Car sat for two years. Put in new battery got car running. Started to overheat because cooling fans will not turn on. It was eighty degrees outside. A friend pulled out some relays and may have plugged them in upside down. Where do I start? Are there fuses also?

Friday, February 16th, 2018 AT 8:57 AM

5 Replies

WRENCHTECH

MECHANIC
20,761 POSTS

What do you mean by "starts" to overheat?

These fans are not programmed to turn on until approx 226 degrees which may seem hot to you but that is entirely intentional on the engineers part. Try turning the AC on and see if that triggers the fans to come on.

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Friday, February 16th, 2018 AT 3:07 PM

NOTAPROMIKE2

MEMBER
32 POSTS

Starts to overheat as in the coolant is boiling into the overflow box and the car is pouring steam, but the motor has not seized up.

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Friday, February 16th, 2018 AT 5:04 PM

WRENCHTECH

MECHANIC
20,761 POSTS

Do the fans turn on with the AC or not?

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Friday, February 16th, 2018 AT 5:07 PM

NOTAPROMIKE2

MEMBER
32 POSTS

No.

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Saturday, February 17th, 2018 AT 7:04 PM

WRENCHTECH

MECHANIC
20,761 POSTS

Okay, sounds like there is an issue with the fan circuit. The best I can do is give you the wiring diagram but you may have to get a local shop to diagnose it for you.
This is a two speed system so it is very surprising that neither speed works.

Here is the diagram.

Image (Click to make bigger)