A/C is not blowing cold air when in idle, but blows fine when I'm driving...any ideas??

 

What year and engine?

Do you have an electric fan? Is it working when the a/c is running? If no electric fan, is the clutch fan working? You'll hear it roar when the engine gets warm.

If there isn't enough air moving over the condenser then your a/c won't work. That's why it may work great at highway speeds and not at all in the city.

If you can, get a gauge set and post the high and low pressures too.

 

its a 2004 auto 3.7 v6

 

Good.

You do have an electric fan. See if it's running with the a/c.

We'll need those pressures if you can get them.

 

My engine overheated today driving around town with the a/c on, but it was fine with the a/c on on the highway...

 

Check your fan clutch. You should hear it roaring when the engine gets hot.