Cooling fan will not come on

Tiny
LRADENHEIMER
  • MEMBER
  • 1992 CHEVROLET CAMARO
  • 5.0L
  • V8
  • AUTOMATIC
  • 108,000 MILES
Cooling fan does not come on as should. With A/C on the fan comes on. If I ground at the thermal switch on engine block it still does not work. If I ground the green wire on the relay the fan runs fine. There looks like there is an ECM module in front of the fan relays. Does the thermal sensor run through this module? Any ideas?
Saturday, May 12th, 2018 AT 9:49 AM

15 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

The coolant temperature sensor is the control for the fan. If you remove the connector while the key is on, it should send a signal of high temperature to the PCM and the fans should kick on.

Check that and see if it happens.

Roy

https://www.2carpros.com/articles/symptoms-of-a-bad-coolant-temperature-sensor

https://www.2carpros.com/articles/how-an-electric-cooling-fan-works
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Saturday, May 12th, 2018 AT 10:32 AM
Tiny
LRADENHEIMER
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I disconnected the sensor and the fan did not come on. My car only has one fan. The sensor is located by the starter on the block is it not. The one by the manifold on driver side is just for the gauge I thought.
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Saturday, May 12th, 2018 AT 10:47 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Do you have a voltmeter to do some checks?

Need to check voltage at the relay to be sure power is available for the fan to run.

Roy
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Saturday, May 12th, 2018 AT 10:51 AM
Tiny
LRADENHEIMER
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  • 8 POSTS
I did check the voltage and it is there on the relay. The only way I could get the fan on was to ground the green and white wire on the relay and the fan would come on.
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Saturday, May 12th, 2018 AT 10:56 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, I would replace the coolant temperature sensor.
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Saturday, May 12th, 2018 AT 11:41 AM
Tiny
LRADENHEIMER
  • MEMBER
  • 8 POSTS
I replaced the coolant sensor and it did not help either.
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Saturday, May 12th, 2018 AT 1:03 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Did you let it warm up to the temperature for the sensor to turn on the fan? It is about 212 degrees for it to turn on.

Roy
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Saturday, May 12th, 2018 AT 1:29 PM
Tiny
LRADENHEIMER
  • MEMBER
  • 8 POSTS
It got up to about 230 by the gauge and I turned the A/C on to bring the fan on to cool it back down.
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Saturday, May 12th, 2018 AT 1:49 PM
Tiny
ASEMASTER6371
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What color are the wires on the coolant sensor?
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Saturday, May 12th, 2018 AT 1:54 PM
Tiny
LRADENHEIMER
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Black and yellow.
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Saturday, May 12th, 2018 AT 2:00 PM
Tiny
ASEMASTER6371
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That is the issue. The switch you need is on the head.

I attached the location of the switch.

Roy
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Saturday, May 12th, 2018 AT 2:03 PM
Tiny
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I can see the wire. Why in the heck would they put it there. That will be tomorrow. I will have to get the car back up on jack stands to get to it. I cannot even get near it on top.
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Saturday, May 12th, 2018 AT 2:19 PM
Tiny
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Lol, that is engineering.
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Saturday, May 12th, 2018 AT 2:24 PM
Tiny
LRADENHEIMER
  • MEMBER
  • 8 POSTS
I installed the new fan switch and plug and the fan works like it should.
Thanks,
Larry
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Sunday, May 13th, 2018 AT 10:12 AM
Tiny
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Good job.

Glad you fixed it. Thanks for using 2CarPros. Com.

Roy
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Sunday, May 13th, 2018 AT 12:22 PM

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