Idling at stop lights the temperature gauge raises

2002 BUICK RENDEZVOUS

195,000 MILES • 3.3L • 6 CYL • AUTOMATIC

JOANNA FRUCHTNICHT FISHER

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I recently bought this car and it does fine on long trips (had to drive it an estimated 160 to get it home). But idling at stop lights the heat gauge raises. It you got a long run between stop lights, it lowers. But if you wait too long at the next one it raises again.
It has a small antifreeze leak, but it's not leaking fast enough to cause this.
A/C is also broken, but I plan to work on that in a few days when I have time to.

Jul 18, 2019 at 10:18 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Welcome to 2CarPros.

If it cools down when moving and overheats when stopped, it sounds like the radiator cooling fan is not turning on. Check to see if you notice them running when it starts getting hot.

Take a look through this link:

https://www.2carpros.com/articles/how-an-electric-cooling-fan-works

Now, if you find they aren't working, we need to check a couple things. First, we need to confirm that fuses 39 and 40 are not blown. Also, check relay 59. These are all located under the hood in the fuse / relay box. I attached a pic and highlighted the things needing checked. I placed an R on the relay. Here are a few links you may find helpful. Also, the last link explains how to check a relay.

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https://www.2carpros.com/articles/how-a-car-fuse-works

https://www.2carpros.com/articles/how-to-check-a-car-fuse

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

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Next is the relay. If you find another relay in the box with the same part number, switch the two and see if the fans work then. Or, here is the link that explains how to check a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know if this helps or if you have other questions.

Take care,
Joe

Image (Click to enlarge)

Jul 18, 2019 at 8:29 PM