Why does my 97 saturn idle high and thermostat drop when at a stop?

Question

When I start my 97 Saturn or come to a stop the engine idles at about 3,000 rpm. I also noticed that my engine temp wont even read when this happens. It is not all the time. Usually after the car has been sitting for a while.

I have also had it overheat on me a few times in the past few weeks. It only happens on hot days when I run the A/C and get stuck at a traffic light. I topped up the coolant each time afterwords.

Any ideas?

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Answer 1

The overheat condition is likely because either a cooling fan isn't running, or it's running too slowly.  This can cause overheating..the fan motors do go bad over time...if you can't feel the air from the fan at the firewall, it's not moving enough air.

High idle is usually an indication of a vacuum leak.  And I'd bet you've damaged the temp sensor with the overheating.