Cooling fans

Tiny
MARYLOPEZ
  • MEMBER
  • 2001 PONTIAC GRAND AM
  • 173,412 MILES
My cooling fans are constantly on. As soon as I start my vehicle and the temperature gauge stays all the way cool. Is this okay for my vehicle and what can I do to it?
Monday, October 9th, 2017 AT 1:42 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,451 POSTS
No that is not good as those fans draw a lot of power. Your description sounds like the coolant temperature sensor has failed. That would keep the temperature gauge down and turn on the fans as a protective measure because the computer does not know the coolants temperature.

If you provide your engine and transmission information I can look for other electrical items that could cause this.
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Monday, October 9th, 2017 AT 11:06 AM
Tiny
MARYLOPEZ
  • MEMBER
  • 22 POSTS
3.4 L LA1 "3400" V6.
Transmission 5-speed Getrag F23 manual.
4-speed 4T40-E automatic.
4-speed 4T45-E automatic.

I know its a 3.4 but have no idea about the transmission.
Thanks
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Tuesday, October 10th, 2017 AT 6:02 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,451 POSTS
Transmission wise the manual means you would have a clutch.

Not a worry as the 3.4 gives me the info I need.

There are 2 scenarios that could be the issue.
One would be that the coolant temperature sensor has failed. This means the computer doesn't know what temperature the engine is at so it "panics" and turns the fans on to keep the engine cool.

The other would be that the fan controls have failed, either a relay or wiring problem has caused the fans to stay on, this would also mean the coolant wouldn't warm up much because of the high airflow across the radiator.

I would lean more toward the first one as the gauge is staying in the cold area and doesn't move up. With a proper thermostat it should at least warm up then drop cold again and cycle that way for a while. Plus both fans have relays and it would be unlikely for them both to stick on.

Replacement isn't difficult, you drain the coolant, Unplug and remove the sensor and install a new one. Then refill with coolant. However I would probably have a shop with a scan tool check the senors output and verify that it is bad before I did that. It could be the sensor wiring has failed or that the reference voltage to it has failed. All of those would make the computer see a failed sensor.
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Wednesday, October 11th, 2017 AT 1:01 PM

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