What are some causes for my a/c to blow warm air when the car is idle?

What is your question?

When my car is idle for too long, the a/c will start blowing warm air even though it is set to cold air. However, if my car is moving the a/c will start to blow cold air again like it is supposed to. What can cause this?

What makes this problem better or worse?

When the car is idle

How long has your 2006 Scion tC had this problem?

A few weeks