My chevy cobalt runs a bit hot 200-210 when sitting,but if air conditioner is on stays cool, what could be my problem?

Might be close to normal. Your thermostat is 180 degree. But Check to see if your fans are coming on when sitting with ac off.

When ac is on sounds like your fans are coming on as they should. Fan should run with ac on and when engine temp increases with ac off.

Every time I see Cobalt I feel compelled to say make sure you have been in for the ignition re-call...people are getting killed

I agree. I got hammered the other day for bringing up the cobalt recall issues. Grammy1 if you have not had your recalls done on this car please do ASAP. Your safety depends on it.

Got me this time..but we agree. 210 is not hot, just a tiny bit on the high end of normal

The radiator fan is not working properly your car may have 1 or 2 fans one is controlled by the temperature computer and the other just turn with the a/c sometimes one fan do all. So first turn the car on with the a/c off and check if the fan turns itself after car warms up, then check with the a/c on if work check the fan relays in the fuse box. Replace them if is necessary (recommended) if still not working you may replace the fan- cause they have a "clutch inside that sometimes get damaged. Good luck !

I remember that guy, chewing your ass for mentioning it while people are dying..I don't know WHAT his problem is.

Lol. It's all good though. I can sleep well at night knowing that I spread the word and did not just sit there with my hand over my mouth.

That would be me. :)

Lol. Good morning. Munron