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Cooling fan problems engine overheats

Tiny
STEETOR
  • MEMBER
  • 1997 OLDSMOBILE AURORA
  • V8
  • FWD
  • AUTOMATIC
  • 127,000 MILES
The engine cooling fans only start when the AC is on, the temperature gauge reaches normal temperature and beyond into the hot range.

It has reached 240, then I turn on the AC so fans turn on. Shouldn't fans turn on about 220? Is it a relay problem? Where is high speed relay located?

There are 2 fans. Both turn-on when AC is engaged. The temp gauge shows temp increase, so temp probe seems OKay. Where is temp sensor located? Where are cooling fans relays located?
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Monday, November 1st, 2010 AT 1:35 PM

20 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,798 POSTS
Hey Steetor,

I have gathered these guides for you to start checking things. This guide shows both the temperature sensor location and the fan relays. The BCM send the signal to the relays so if all else fails the BCM is bad but check the wiring diagrams first to be sure.

The fan relay locations are in the diagram. You might have to use an infrared non-contact thermometer to see if engine temp and gauge show about the same to make sure of the engine's temperature.

https://www.2carpros.com/articles/how-to-use-an-infrared-temperature-meter

and

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please let us know what you find so it will help others.

Best, Ken

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Tuesday, December 6th, 2016 AT 8:54 PM
Tiny
RCA_821
  • MEMBER
  • 1 POST
  • 1997 OLDSMOBILE AURORA
Engine Cooling problem
1997 Oldsmobile Aurora V8 Front Wheel Drive Automatic

I'm having problems with my cooling fans. They activate and work fine when I turn the a/c on, but when I don't use the a/c the fans don't come on. The car seems to overheat when I don't use the a/c.
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Check for faulty cooling fan relay(s) and engine coolant temperature sensor
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Since they come on, the relays can be assumed good. They default on with A/C to keep airflow across the condenser when stopped. The question is, what is the coolant temp sensor registering, and what indication of overheat are you getting. The fans should come on low speed at 229 deg(F), and high speed 234 deg. They are controlled by the PCM, so if the pcm is seeing this temp, the fans should be on. I would approach this by having the system scanned for PCM trouble codes. If there are none relevant I would try and read coolant temp sensor data with a scan tool, and at the least have the cooling system tested for combustion gas presence.
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
MDCALIFORNIA
  • MEMBER
  • 1 POST
  • 1997 OLDSMOBILE AURORA
  • V8
  • FWD
  • AUTOMATIC
  • 48,000 MILES
I have recently acquired a 1997 Olds Aurora. I am having problems with it running hot. The cooling fans only seem to work when the AC is on. If I drive around with the AC off, the fans don't come on. It has been taken to a Cadillac Dealership and they say nothing is wrong. Does anybody have an idea?
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,117 POSTS
It should come on regardless of the AC after the engine temp reaches a certain point. Have you checked the temp sensor?
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
ERIC GIEBLER
  • MEMBER
  • 1 POST
  • 1998 OLDSMOBILE AURORA
  • V8
  • FWD
  • AUTOMATIC
  • 199,000 MILES
Why would the fuse for my cooling fans keep blowing
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It keeps blowing because there is eitehr a short in the fans or one of the wires that are hot leading to the fans is shorting out against ground. You'll need to get it checked for draw
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Tuesday, October 30th, 2018 AT 4:34 PM (Merged)
Tiny
SUGARDEL1
  • MEMBER
  • 1 POST
  • 2001 OLDSMOBILE AURORA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 167,000 MILES
FANS ARE NOT OPERATING. MOTORS ARE GOOD. WHERE IS THE ENGINE COOLANT TEMP SENSOR? THANKS
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
For the 3.5L and 4.0L engines it is located at the rear of the right cylinder head. 4.0L engine's ECT sensor is pictured below..


https://www.2carpros.com/forum/automotive_pictures/261618_Noname_382.jpg



Also inspect cooling fan relays..

Thanks for using 2CarPros.com!
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
DEBORAH ALONZO
  • MEMBER
  • 3 POSTS
  • 1995 OLDSMOBILE AURORA
  • V8
  • FWD
  • AUTOMATIC
  • 25,000 MILES
Cooling fans are not turning on so it's making the car overheat and die out?
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
BDOGG0070
  • MECHANIC
  • 42 POSTS
Check the fuses first off if not that then possible fusible link, relay, bad motor or temp sensor. Sorry wish I could narrow it down. Kinda hard to do that without the car in front of me.
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Could also be the computer-take your advice and comeback with some results if it continues
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
DEBORAH ALONZO
  • MEMBER
  • 3 POSTS
Checked the relays and changed the temperture sensor but it is still doing it. The fans will not come on what do u suggest I should do next?
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
DEBORAH ALONZO
  • MEMBER
  • 3 POSTS
Where do I find the fusible links at? We checked the electrical scamatic but all we found was the fuses and relays. So where should I look to find them?
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
MEYERS
  • MEMBER
  • 1 POST
  • 1999 OLDSMOBILE AURORA
  • 92,000 MILES
Fans won't come on
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Radiator fan? If you turn on the ac will the fan run? If you unplug the coolant temp sensor will the fan run?
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Just to add, did you check applicable fuses? Hope you can read the diagram?
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
DDYSART
  • MEMBER
  • 1 POST
  • 1995 OLDSMOBILE AURORA
  • V8
  • 2WD
  • AUTOMATIC
  • 125,698 MILES
I can't find the sensor that cutson both electric fans, and I also need to know the fuse location for the fans. Thanks in advance
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Your vehicle has 3 cooling fan relays. Need to test them all. Two are located in right front underhood relay center, the other is located at center rear of engine compartment.
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Tuesday, October 30th, 2018 AT 4:35 PM (Merged)

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