no air conditioning when idle

If I am in a drive thru, waiting for a train or even sometimes at red lights-my air will suddenly blow warm. (not a good thing for those of us in this hot texas summer).

Is there 2 fans for this and could it possibly be something as simple as a fuse?

Check your fan and see if it turns on when you turn the A/C on. The fan should start when the A/C is on to avoid overheating.