I have a 2011 Chevrolet Equinox. I changed the coolant sensor, and the coolant level is fine. This problem is intermittent, which is aggravating. I feel it is an electrical issue and would like to know if anyone has had any experience with it. I don’t think it’s the thermostat, however, because the problem sometimes goes away after around 10 miles. Then goes happens again. Any suggestions?
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It could still be the thermostat. A bad thermostat will still function, but not to its full potential.
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Possible air in the line and the fluid is having issues moving/flowing.
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It’s a poor thermostat that is slow to open when required.
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All you had to say was equinox
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If it only overheats at idle and then cools down once you get moving, I’d start with cooling fans, then radiator, and possibly a water pump. If it overheats for approximately 10 minutes before returning to normal and remaining there, the thermostat is most likely the culprit.
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It’s very conceivable that the sensor is for the ambient air temperature. I just had a terrible diagnosis, similar to yours. It would be fine to blow cold, but then randomly blow hot, and the coolant sensor would read wrongly. The air conditioner detects if the outside temperature is too chilly or hot and shuts itself off. The ambient air sensor is located behind the front bumper, and unless it is consistently reading wrong, it will display and test normally. It’s also really inexpensive, costing about $12 locally. Of course, this is just supposition because I haven’t tested or read any data from it.
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Thank you for this. I am lucky to see this as the first post. 
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Thanks. I’ll try this before replacing the thermostat. Do you have an equinox, as well?
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Ya it’s the thermostat
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Same thing happens to mine. 2010 Chevy equinox
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What did you do to fix it?
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If you already replaced ECT sensor it’s 99% the thermostat
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