What does the cooling fan relay switches do?

Cheri DeMonico

Asked by Jan 11, 2016 at 08:42 PM about the 1988 Chevrolet Corvette Coupe

Question type: Maintenance & Repair

I have one in the center under the throttle body, a relay switch near the windshiled on the driver's side clearly visible, and I believe there's 2 more that I seen on the passenger's side.  Can you explain what they do?  I believe they cool down the engine when it gets to a certain temp and then shut back off -- for the radiator I believe.   Can I just bypass these switches as they tend to go bad and just have the radiator fan run upon starting the engine this way I won't overheat the car and my temp always stays below 190 or 180?  I live in South Florida and it's HOT here all year around...

5 Answers


The purpose of a relay is to switch on power to something. A small amount of power is put to the relay which causes it to switch on a larger amount of power to the intended device. In this case the temperature sensor sends a small amount of power to the relay which then turns on the cooling fan. Not all those relays you see are for the cooling fan, they are for other purposes.

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Best Answer
Cheri DeMonico

Now, my next question: How do you test each one to see if they are in fact bad? With the switch still plugged in, can I use an electrical tester? I haven't changed them out since I've had the car since 1994... Should I change them? My cooling fan isn't switching on any longer.... Thanks for your help.


Yes you can test relays but I find the best way is to switch out a working relay with the suspect relay to see if there is any change. If it were my car I would just install a new relay to see if the cooling fan switches on. http://www.agcoauto.com/content/news/p2_articleid/245

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Cheri DeMonico

Full of Regrets: Thank you SO MUCH. You helped me a lot.. I'm going to be busy this weekend! Take care!

1 out of 1 people think this is helpful.

Good luck to you!

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