I have a 2007 town / country that blows cold air when at idle.
Things to check:
Is the engine fan running slowly at idle? If so, its a sign that it needs replacement.
Is there a funny smell in the cabin? Refrigerant tends to slowly leak and has a weird smell. Have a friend smell the cabin air in case you got used to the smell (due to driving it all the time).
For more and better help we will need a bit more info.