I'm with you Lifnprogres. I have a 2004 Cavalier that had the same problem - a/c blew warm when idling - cooled car when driving. I noticed the radiator cooling fan wasn't running when the a/c was switched on. (The fan is designed to always run when a/c is on). So I took your advice and bought a new radiator fan motor for $25 at O'Reillys. The new fan started running immediately upon turning on the a/c. I now have plenty of cold air when idling. Problem solved. Thanks for the advice, Lifnprogres.