Chrysler Repair: 2005 T&C a/c not blowing, speed right, beginning of spring

Question
I have a 2005 T&C where the a/c just quit blowing it did this at the beginning of spring and I took it to the dealer and they replaced the relay I believe but a few days ago it has done the samething again. What could be causing this? I don't want to take it back to them just for them to replace the same part and it go out again. When you are driving cold air will come through the vents just fine but as soon as you stop no more air flow. Any suggestions?

Answer
humm  the last line is a bit confusing to me  u say the air  or cold air will blow until u stop the car  correct? Does the blower motor keep turning when u come to a stop. The relay that they replaced  that was because it would not work unless it was on #4 speed right?